Chapter 26

HISTOLOGICAL METHODS.

In the more exact investigations of the tissues, it is often necessary to have recourse to other reagents than those we have used hitherto, in order to bring out plainly the more obscure points of structure. This is especially the case in studies in cell division in the higher plants, where the changes in the dividing nucleus are very complicated.

For studying these the most favorable examples for ready demonstration are found in the final division of the pollen spores, especially of some monocotyledons. An extremely good subject is offered by the common wild onion (_Allium Canadense_), which flowers about the last of May. The buds, which are generally partially replaced by small bulbs, are enclosed in a spathe or sheath which entirely conceals them. Buds two to three millimetres in length should be selected, and these opened so as to expose the anthers. The latter should now be removed to a slide, and carefully crushed in a drop of dilute acetic acid (one-half acid to one-half distilled water). This at once fixes the nuclei, and by examining with a low power, we can determine at once whether or not we have the right stages. The spore mother cells are recognizable by their thick transparent walls, and if the desired dividing stages are present, a drop of staining fluid should be added and allowed to act for about a minute, the preparation being covered with a cover glass. After the stain is sufficiently deep, it should be carefully withdrawn with blotting paper, and pure water run under the cover glass.

The best stain for acetic acid preparations is, perhaps, gentian violet. This is an aniline dye readily soluble in water. For our purpose, however, it is best to make a concentrated, alcoholic solution from the dry powder, and dilute this as it is wanted. A drop of the alcoholic solution is diluted with several times its volume of weak acetic acid (about two parts of distilled water to one of the acid), and a drop of this mixture added to the preparation. In this way the nucleus alone is stained and is rendered very distinct, appearing of a beautiful violet-blue color.

If the preparation is to be kept permanently, the acid must all be washed out, and dilute glycerine run under the cover glass. The preparation should then be sealed with Canada balsam or some other cement, but previously all trace of glycerine must be removed from the slide and upper surface of the cover glass. It is generally best to gently wipe the edge of the cover glass with a small brush moistened with alcohol before applying the cement.

If the spore mother cells are still quite young, we shall find the nucleus (Fig. 127, _A_, _n_) comparatively small, and presenting a granular appearance when strongly magnified. These granules, which appear isolated, are really parts of filaments or segments, which are closely twisted together, but scarcely visible in the resting nucleus. On one side of the nucleus may usually be seen a large nucleolus (called here, from its lateral position, paranucleus), and the whole nucleus is sharply separated from the surrounding protoplasm by a thin but evident membrane.

The first indication of the approaching division of the nucleus is an evident increase in size (_B_), and at the same time the colored granules become larger, and show more clearly that they are in lines indicating the form of the segments. These granules next become more or less confluent, and the segments become very evident, appearing as deeply stained, much-twisted threads filling the nuclear cavity (Fig. 127, _C_), and about this time the nucleolus disappears.

The next step is the disappearance of the nuclear membrane so that the segments lie apparently free in the protoplasm of the cell. They arrange themselves in a flat plate in the middle of the cell, this plate appearing, when seen from the side, as a band running across the middle of the cell. (Fig. 127, _D_, shows this plate as seen from the side, _E_ seen from above.)

About the time the nuclear plate is complete, delicate lines may be detected in the protoplasm converging at two points on opposite sides of the cell, and forming a spindle-shaped figure with the nuclear plate occupying its equator. This stage (_D_), is known as the "nuclear spindle." The segments of the nuclear plate next divide lengthwise into two similar daughter segments (_F_), and these then separate, one going to each of the new nuclei. This stage is not always to be met with, as it seems to be rapidly passed over, but patient search will generally reveal some nuclei in this condition.

Although this is almost impossible to demonstrate, there are probably as many filaments in the nuclear spindle as there are segments (in this case about sixteen), and along these the nuclear segments travel slowly toward the two poles of the spindle (Fig. 128, _A_, _B_). As the two sets of segments separate, they are seen to be connected by very numerous, delicate threads, and about the time the young nuclei reach the poles of the nuclear spindle, the first trace of the division wall appears in the form of isolated particles (microsomes), which arise first as thickenings of these threads in the middle of the cell, and appear in profile as a line of small granules not at first extending across the cell, but later, reaching completely across it (Fig. 128, _C_, _E_). These granules constitute the young cell wall or "cell plate," and finally coalesce to form a continuous membrane (Fig. 128, _F_).

The two daughter nuclei pass through the same changes, but in reverse order that we saw in the mother nucleus previous to the formation of the nuclear plate, and by the time the partition wall is complete the nuclei have practically the same structure as the first stages we examined (Fig. 128, _F_).[15]

[15] The division is repeated in the same way in each cell so that ultimately four pollen spores are formed from each of the original mother cells.

This complicated process of nuclear division is known technically as "karyokinesis," and is found throughout the higher animals as well as plants.

The simple method of fixing and staining, just described, while giving excellent results in many cases, is not always applicable, nor as a rule are the permanent preparations so made satisfactory. For permanent preparations, strong alcohol (for very delicate tissues, absolute alcohol, when procurable, is best) is the most convenient fixing agent, and generally very satisfactory. Specimens may be put directly into the alcohol, and allowed to stay two or three days, or indefinitely if not wanted immediately. When alcohol does not give good results, specimens fixed with chromic or picric acid may generally be used, and there are other fixing agents which will not be described here, as they will hardly be used by any except the professional botanist. Chromic acid is best used in a watery solution (five per cent chromic acid, ninety-five per cent distilled water). For most purposes a one per cent solution is best; in this the objects remain from three or four to twenty-four hours, depending on size, but are not injured by remaining longer. Picric acid is used as a saturated solution in distilled water, and the specimen may remain for about the same length of time as in the chromic acid. After the specimen is properly fixed it must be thoroughly washed in several waters, allowing it to remain in the last for twenty-four hours or more until all trace of the acid has been removed, otherwise there is usually difficulty in staining.

As staining agents many colors are used. The most useful are hæmatoxylin, carmine, and various aniline colors, among which may be mentioned, besides gentian violet, safranine, Bismarck brown, methyl violet. Hæmatoxylin and carmine are prepared in various ways, but are best purchased ready for use, all dealers in microscopic supplies having them in stock. The aniline colors may be used either dissolved in alcohol or water, and with all, the best stain, especially of the nucleus, is obtained by using a very dilute, watery solution, and allowing the sections to remain for twenty-four hours or so in the staining mixture.

Hæmatoxylin and carmine preparations may be mounted either in glycerine or balsam. (Canada balsam dissolved in chloroform is the ordinary mounting medium.) In using glycerine it is sometimes necessary to add the glycerine gradually, allowing the water to slowly evaporate, as otherwise the specimens will sometimes collapse owing to the too rapid extraction of the water from the cells. Aniline colors, as a rule, will not keep in glycerine, the color spreading and finally fading entirely, so that with most of them the specimens must be mounted in balsam.

Glycerine mounts must be closed, which may be done with Canada balsam as already described. The balsam is best kept in a wide-mouthed bottle, specially made for the purpose, which has a glass cap covering the neck, and contains a glass rod for applying the balsam.

Before mounting in balsam, the specimen must be completely freed from water by means of absolute alcohol. (Sometimes care must be taken to bring it gradually into the alcohol to avoid collapsing.[16]) If an aniline stain has been used, it will not do to let it stay more than a minute or so in the alcohol, as the latter quickly extracts the stain. After dehydrating, the specimen should be placed on a clean slide in a drop of clove oil (bergamot or origanum oil is equally good), which renders it perfectly transparent, when a drop of balsam should be dropped upon it, and a perfectly clean cover glass placed over the preparation. The chloroform in which the balsam is dissolved will soon evaporate, leaving the object embedded in a transparent film of balsam between the slide and cover glass. No further treatment is necessary. For the finer details of nuclear division or similar studies, balsam mounts are usually preferable.

[16] For gradual dehydrating, the specimens may be placed successively in 30 per cent, 50 per cent, 70 per cent, 90 per cent, and absolute alcohol.

It is sometimes found necessary in sectioning very small and delicate organs to embed them in some firm substance which will permit sectioning, but these processes are too difficult and complicated to be described here.

* * * * *

The following books of reference may be recommended. This list is, of course, not exhaustive, but includes those works which will probably be of most value to the general student.

1. GOEBEL. Outlines of Morphology and Classification.

2. SACHS. Physiology of Plants.

3. DE BARY. Comparative Anatomy of Ferns and Phanerogams.

4. DE BARY. Morphology and Biology of Fungi, Mycetozoa, and Bacteria.

These four works are translations from the German, and take the place of Sachs's Text-book of Botany, a very admirable work published first about twenty years ago, and now somewhat antiquated. Together they constitute a fairly exhaustive treatise on general botany.--New York, McMillan & Co.

5. GRAY. Structural Botany.--New York, Ivison & Co.

6. GOODALE. Physiological Botany.--New York, Ivison & Co.

These two books cover somewhat the same ground as 1 and 2, but are much less exhaustive.

5. STRASBURGER. Das Botanische Practicum.--Jena.

Where the student reads German, the original is to be preferred, as it is much more complete than the translations, which are made from an abridgment of the original work. This book and the next (7 and 8) are laboratory manuals, and are largely devoted to methods of work.

7. ARTHUR, BARNES, and COULTER. Plant Dissection.--Holt & Co., New York.

8. WHITMAN. Methods in Microscopic Anatomy and Embryology.--Casino & Co., Boston.

For identifying plants the following books may be mentioned:--

Green algæ (exclusive of desmids, but including _Cyanophyceæ_ and _Volvocineæ_).

WOLLE. Fresh-water Algæ of the United States.--Bethlehem, Penn.

Desmids. WOLLE. Desmids of the United States.--Bethlehem, Penn.

The red and brown algæ are partially described in FARLOW'S New England Algæ. Report of United States Fish Commission, 1879.--Washington.

The _Characeæ_ are being described by Dr. F. F. ALLEN of New York. The first part has appeared.

The literature of the fungi is much scattered. FARLOW and TRELEASE have prepared a careful index of the American literature on the subject.

Mosses. LESQUEREUX and JAMES. Mosses of North America.--Boston, Casino & Co.

BARNES. Key to the Genera of Mosses.--Bull. Purdue School of Science, 1886.

Pteridophytes. UNDERWOOD. Our Native Ferns and their Allies.--Holt & Co., New York.

Spermaphytes. GRAY. Manual of the Botany of the Northern United States. 6th edition, 1890. This also includes the ferns, and the liverworts.--New York, Ivison & Co.

COULTER. Botany of the Rocky Mountains.--New York, Ivison & Co.

CHAPMAN. Flora of the Southern United States.--New York, 1883.

WATSON. Botany of California.

INDEX.

_Acacia_, 209.

_Acer_, _-aceæ_. See "Maple."

Acetic acid, 3, 59, 98, 138, 230.

_Achimenes_, 218.

_Acorus_. See "Sweet-flag."

Actinomorphic, 213.

Adder-tongue, 116; Fig. 70. See also "_Erythronium_."

_Adiantum_. See "Maiden-hair."

_Adlumia_. See "Mountain-fringe."

_Æsculinæ_, 199.

_Æsculus_. See "Buckeye," "Horse-chestnut."

_Aggregatæ_, 222.

Alcohol, 5, 31, 55, 83, 230, 233.

Algæ, 4, 21. green, 21. red, 21, 49. brown, 21, 41.

Alga-fungi. See "_Phycomycetes_."

_Alisma_, _-ceæ_. See "Water-plantain."

_Allium_. See "Wild onion."

Amaranth, 185.

_Amarantus_, _-aceæ_. See "Amaranth."

_Amœba_, 7; Fig. 2.

_Ampelidæ_. See "Vine."

_Ampelopsis_. See "Virginia creeper."

Anatomy, 3. gross, Implements for study of, 3. minute, Implements for study of, 3, 4.

Anatropous, 151.

_Andreæaceæ_, 99, 100.

Andrœcium, 148.

_Andromeda_, 211.

_Anemone_, 185.

_Angiocarpæ_, 84.

Angiosperm, 129, 143, 145.

Aniline colors, 233.

_Anisocarpæ_, 210, 213.

_Anonaceæ_. See "Custard-apple."

Anther, 148, 175, 179.

Antheridium, 27, 36, 39, 45, 51, 59, 68, 89, 96, 106, 122.

_Anthoceros_, _Anthoceroteæ_, 91; Fig. 57.

_Aphanocyclæ_, 185, 196.

_Aplectrum_, 167; Fig. 90.

_Apocynum_, _-aceæ_. See "Dog-bane."

_Apostasieæ_, 164.

Apple, 145, 171, 206; Fig. 114.

Apricot, 207.

_Aquilegia_. See "Columbine."

_Aralia_, _-aceæ_. See "Spikenard."

Archegonium, 89, 97, 105, 122, 133, 140, 144.

Archicarp, 138, 145.

_Arcyria_, 13; Fig. 5.

_Arethusa_, _Arethuseæ_, 166; Fig. 90.

_Argemone_, 191.

Aril, 189.

_Arisæma_, 78, 157; Fig. 86.

_Aristolochia_, _-aceæ_, 224.

Aroid, _Aroideæ_, 157.

Arrow-grass, 167.

Arrowhead, 167; Fig. 91.

Arrowroot, 163.

_Asarum_. See "Wild ginger."

_Asclepias_, _-daceæ_. See "Milk-weed."

_Ascobolus_, 71-73; Fig. 43. culture of, 71. spore fruit, 71. archicarp, 71. spore sacs, 72.

_Ascomycetes_, 65, 66.

Ascospore, 66.

Ascus, 66, 69.

Ash, 218; Fig. 122.

_Asimina_. See "Papaw."

_Aspidium_, Fig. 70.

_Asplenium_, 104; Fig. 70.

Aster, 224.

_Atropa_. See "Deadly nightshade."

Axil, 174.

Azalea, 210; Fig. 116.

_Azolla_, 117; Fig. 71.

Bacteria, 15, 17, 19; Fig. 8.

Balsam, _Balsamineæ_, 198.

Bamboo, 162.

_Bambusa_. See "Bamboo."

Banana, 163.

Barberry, 17, 187; Fig. 101.

Bark. See "Cortex."

_Basidiomycetes_, 77.

Basidium, 77, 80, 83.

Basswood, 195; Fig. 106.

Bast. See "Phloem."

_Batatas_. See "Sweet-potato."

_Batrachospermum_, 53; Fig. 31.

Bean, 207, 208.

Bear-grass. See "_Yucca_."

Bee, 227, 228.

Beech, 183.

Beech-drops, 218.

Beet, 184.

Beggar's-ticks, 215.

Begonia, 3, 205.

Bell-flower, 220, 226; Fig. 123.

Bellwort, 156.

_Berberis_, _-ideæ_. See "Barberry."

Bergamot oil, 234.

Berry, 145, 156.

_Betulaceæ_, 183.

_Bicornes_, 210.

_Bignonia_, _-aceæ_, 218.

Biology, 2.

Birch, 183.

Bird's-nest fungus. See "_Cyathus_."

Bishop's cap, 202; Fig. 111.

Bismarck brown, 233.

Bitter-sweet, 199; Fig. 109.

Black alder, 199.

Blackberry, 207.

Black fungi. See "_Pyrenomycetes_."

Bladder-nut, 199; Fig. 108.

Bladder-weed, 33, 217; Fig. 120.

Bleeding-heart. See "_Dicentra_."

Blood-root, 191; Fig. 103.

Blue-eyed grass, 156.

Blue-flag. See "_Iris_."

Blue-green slime, 15.

Blue valerian. See "_Polemonium_."

Borage, 215.

_Borragineæ_. See "Borage."

Bordered pits, 138.

Botany defined, 2. systematic, 3.

_Botrychium_. See "Grape fern."

Box, 201.

Bract, 199, 222, 229.

_Brasenia_. See "Water-shield."

Breathing pore, 91, 99, 113, 130, 147, 150, 177.

_Bromeliaceæ_, 156.

Bryophyte, 86.

Buck-bean, 218.

Buckeye, 171, 199.

Buckthorn, 199.

Buckwheat, 184.

Budding, 64.

_Bulbochæte_, 28; Fig. 16.

Bulb, 146, 153, 172.

Bulrush, 161; Fig. 87.

Bundle-sheath, 110, 176.

Burning-bush. See "Spindle-tree."

Bur-reed, 159; Fig. 86.

Buttercup, 181, 185; Fig. 99.

Butterfly, 227, 228.

Button-bush, 223.

Buttonwood. See "Sycamore."

_Buxus_, _Buxaceæ_. See "Box."

Cabbage, 192.

_Cabombeæ_, 190.

Cactus, _Cactaceæ_, 203; Fig. 112.

_Cæsalpineæ_, 210.

Calcium, 2.

Calla, 157, 229.

_Callithamnion_, 50-52; Fig. 29. general structure, 51. tetraspores, 51. procarp, 51. antheridium, 51. spores, 52.

_Callitriche_, _-chaceæ_. See "Water starwort."

_Calluna_. See "Heath."

_Calopogon_, 166; Fig. 91.

_Calycanthus_, _-aceæ_, 187; Fig. 100.

_Calycereæ_, 223.

_Calycifloræ_, 200.

Calyx, 174, 182.

Cambium, 137-138, 175.

_Campanula_. See "Bell-flower."

_Campanulaceæ_, 220.

_Campanulinæ_, 220.

Canada balsam, 230-234.

Canada thistle, 224; Fig. 125.

_Canna_, _-aceæ_, 162, 163; Fig. 88.

Caper family, 194.

_Capparis_, _-ideæ_. See "Caper."

_Caprifoliaceæ_, 223.

_Capsella_. See "Shepherd's-purse."

Caraway, 202.

Carbon, 2, 95.

Carbon-dioxides, 95.

Cardinal-flower. See "Lobelia."

_Carex_, 161; Fig. 87.

Carmine, 25, 233.

Carnation, 185.

Carpel, 148, 154, 175, 179.

Carpophyll. See "Carpel."

Carpospore, 51-53.

Carrot, 202.

_Caryophylleæ_. See "Pink."

_Caryophyllus_. See "Clove."

_Castalia_, 189.

Castor-bean, 200.

Catalpa, 218.

Cat-brier, 154.

Catkin, 181.

Catnip, 215.

Cat-tail, 159.

Cedar apple, Cedar rust. See "_Gymnosporangium_."

_Celastraceæ_, 199.

_Celastrus_. See "Bitter-sweet."

Celery, 3.

Cell, 6. apical, 38, 96, 105, 115. division, 23, 31, 229. row, 8; Fig. 3. mass, 8; Fig. 4. sap, 6, 151.

Cellulose, 3.

Centaury, 219.

_Centrospermæ_, 183.

_Cephalanthus_. See "Button-bush."

_Cerastium_. See "Chick-weed."

_Ceratophyllum_. See "Horned pond-weed."

_Cercis_. See "Red-bud."

_Chamærops_. See "Palmetto."

_Chara_, 38-40; Fig. 23. general structure, 38. method of growth, 39. cortex, 39. non-sexual reproduction, 39. oögonium, 39. antheridium, 39, 40. spermatozoids, 40. germination, 40.

_Characeæ_, 21, 37, 40.

_Chareæ_, 40.

_Cheiranthus_. See "Wall-flower."

_Chenopodium_, _-aceæ_. See "Goose-foot."

Cherry, 15, 206; Fig. 114.

Chicory, 223.

Chick-weed, 185; Fig. 98.

_Chimaphila_. See "Prince's pine."

_Chionanthus_. See "Fringe-tree."

Chlorine, 2.

_Chlorococcum_, 23; Fig. 12.

Chloroform, 234.

Chloroplast, 22, 45.

Chlorophyll, 15.

Chlorophyll body. See "Chloroplast."

_Chlorophyceæ_, 21.

_Chondrus_. See "Irish moss."

_Choripetalæ_, 181, 208.

Chromic acid, 25-35, 233.

Chromoplast, 150.

_Cicinnobulus_, 69; Fig. 39.

Cilium, 8.

Cinquefoil, 206.

_Cistaceæ_. See "Rock-rose."

_Cistifloræ_, 192.

Citron, 196.

_Citrus_. See "Orange," "Lemon."

_Cladophora_, 24, 25. structure of cells, 25. nuclei, 25. cell division, 25. zoöspores, 25.

Classification, 3-9.

_Clavaria_, 85; Fig. 51.

_Claytonia_. See "Spring-beauty."

Clematis, 185.

Climbing plants, 171.

_Closterium_, 33; Fig. 20.

Clove, 205.

Clove oil, 234.

Clover, 207.

Club moss, 116. larger, 116. smaller, 123-126; Fig. 74. gross anatomy, 125. spores, 126. prothallium, 126. systematic position, 126.

Cluster-cup, 78.

_Cocos_. See "Palm-coco," 159.

_Coleochæte_, 28; Fig. 17.

Collateral fibro-vascular bundle, 135.

_Collema_, 76; Fig. 44.

Columella, 55.

Columbine, 186; Fig. 99.

Column, 165.

_Columniferæ_, 195.

_Commelyneæ_, 157.

_Compositæ_, 223, 224.

Compound flower, 224. leaf, 159, 170.

Conceptacle, 45.

Cone, 131.

_Conferva_, 26.

_Confervaceæ_, 21, 24.

Conidium, 68.

Conifer, 129, 140, 141.

_Coniferæ_. See "Conifer."

_Conjugatæ_, 22-29.

Connective, 148.

_Conocephalus_. See "Liverwort, giant."

_Contortæ_, 218.

_Convolvulaceæ_, 213.

_Convolvulus_. See "Morning-glory."

_Coprinus_, 82-84; Fig. 48. general structure, 82, 83. young spore fruit, 83. gills basidia, 83. spores, 84.

Coral root, 167.

_Corallorhiza_. See "Coral root."

Coriander, 202.

Corn, 160, 161.

_Cornus_, _-aceæ_. See "Dogwood."

Corolla, 174, 182.

Cortex, 39, 130.

_Corydalis_, 192.

Cotton, 195.

Cotyledon, 134, 146, 180.

Cowslip, 211.

Coxcomb, 185.

Crab-apple, 77, 80.

Cranberry, 211.

_Crassulaceæ_, 203.

Crane's-bill, 3, 196; Fig. 107.

Cress, 192.

_Croton_, 200.

_Cruciferæ_. See "Mustard family."

_Crucifloræ_. See "_Rhœadinæ_."

Cucumber, 221.

Cucumber-tree. See "Magnolia."

_Cucurbitaceæ_. See "Gourd."

Cup fungi ("_Discomycetes_"), 71.

_Cupuliferæ_, 183.

Curl, 66.

Currant, 203.

_Cuscuta_. See "Dodder."

Custard-apple, 186.

_Cyanophyceæ_. See "Blue-green slime."

_Cyathus_, 84; Fig. 50.

_Cycad_, _-eæ_, 140.

_Cycas revoluta_, 141; Fig. 71.

_Cyclamen_, 212.

_Cynoglossum_. See "Hound's-tongue."

_Cyperaceæ_. See "Sedge."

_Cyperus_, 161.

Cypress, 142.

_Cypripedium_. See "Lady's-slipper."

_Cystopus_. See also "White rust." _bliti_, 57; Fig. 33. general structure, 57. structure of filaments, 57. non-sexual spores (conidia), 57. germination of conidia, 58. resting spores, 59. oögonium, 59. antheridium, 59. _candidus_, 60; Fig. 34.

Daisy, 223.

Dandelion, 66, 223; Fig. 125.

_Darlingtonia_, 195.

_Datura_. See "Stramonium."

Day lily, 155.

Deadly nightshade, 215.

Dead nettle, 215; Fig. 120.

_Delphinium_. See "Larkspur."

Dermatogen, 176.

Desmid, 33, 34; Fig. 20.

Devil's apron. See "_Laminaria_."

_Dianthus_. See "Pink."

_Diatomaceæ_, 41, 42; Figs. 24, 25. structure, 42. movements, 42. reproduction, 42.

_Dicentra_, 192; Fig. 103.

Dicotyledon, 145, 170, 181, 225.

_Digitalis_. See "Foxglove."

Diœcious, 88.

_Dionæa_. See "Venus's fly-trap."

_Dioscoreæ_. See "Yam."

_Dioscorea villosa_, 154.

_Diospyros_. See "Persimmon."

_Diospyrinæ_, 210.

_Dipsacus_, _-aceæ_. See "Teasel."

_Dirca_. See "Moosewood."

Ditch-moss, 167; Fig. 91.

Dodder, 214.

_Dodecatheon_. See "Shooting-star."

Dog-bane, 219; Fig. 122.

Dogwood, 202, 229; Fig. 110.

_Draparnaldia_, 26; Fig. 14.

_Drosera_ _-aceæ_. See "Sun-dew."

Drupe. See "Stone-fruit."

Duck-weed, 159; Fig. 86.

Dutchman's pipe. See "_Aristolochia_."

Earth star. See "_Geaster_."

_Ebenaceæ_ (ebony), 212.

_Echinospermum_. See "Beggar's-ticks."

_Ectocarpus_, 45, 47; Fig. 28.

Eel-grass, 168, 169; Fig. 91.

Egg apparatus, 144.

Egg cell, 27, 36, 39, 45, 90, 106, 133, 144.

Egg-plant, 215.

Eichler, 153.

Elater, 91, 122.

Elder, 224.

_Elæagnaceæ_, 206.

Elm, 183.

_Elodea_. See "Ditch-moss."

Embryo, 90, 97, 107, 133, 149, 180.

Embryology, 3.

Embryo sac, 143, 144, 151.

_Enantioblastæ_, 153, 156; Fig. 85.

Endosperm, 133, 146, 152.

Entire leaves, 170.

_Entomophthoreæ_, 57.

_Epacrideæ_, 210.

Epidermis, 91, 111, 112, 113, 122, 135, 137, 150, 177.

_Epigæa_. See "Trailing arbutus."

_Epilobium_. See "Willow-herb."

_Epiphegus_. See "Beech-drops."

Epiphyte, 166.

_Equisetum_, _-tinæ_. See "Horse-tail."

Ergot, 76.

_Erica_, _-aceæ_. See "Heath."

_Erysiphe_, 70.

_Erythræa_. See "Centaury."

_Erythronium_, 146-152; Fig. 81. leaf, 146. stem, 146. root, 146. gross anatomy of stem, 147. flower, 148. fruit and seed, 150. histology of stem, 150. of leaf, 150. of flower, 151. of ovule and seed, 151, 152.

_Eschscholtzia_, 191.

_Eucalyptus_, 206.

_Eucyclæ_, 196, 200.

_Eudorina_, 20.

_Euglena_, 11, 19; Fig. 9.

_Euonymus_. See "Spindle-tree."

_Euphorbia_, 199; Fig. 109.

_Eurotium_, 70; Fig. 42.

Evening primrose, 206.

_Exoascus_, 66.

_Fagopyrum_. See "Buckwheat."

Feather-veined. See "Pinnate-veined."

Fern, 5, 102, 104, 116. flowering, 118; Fig. 70. lady, 104; Fig. 70. maiden-hair. See "Maiden-hair fern." ostrich. See "Ostrich-fern." sensitive, 104. true, 117. water. See "Water-fern."

Fertilization, 225.

Fibre, 124, 175, 177.

Fibro-vascular bundle, 107, 110, 121, 123, 135, 136, 147, 150, 159, 174.

Fig, 183.

Figwort, 215, 216; Fig. 120.

Filament (of stamen), 148, 17.

_Filices_. See "True ferns."

_Filicineæ_. See "Fern."

Fir, 142.

Fission, 23.

_Flagellata_, 19.

Flagellum, 19.

Flax, 197; Fig. 107.

Flies, 229.

Flower, 128, 131.

Flowering-plant. See "Spermaphyte."

Forget-me-not, 215.

Four-o'clock, 183.

Foxglove, 217.

_Frangulinæ_, 199.

_Fraxinus_. See "Ash."

Fringe-tree, 218; Fig. 122.

Fruit, 145.

_Fucaceæ_, 43.

Fuchsia, 201.

_Fucus_, 42-46. _vesiculosus_, 43; Figs. 26, 27. general structure, 43, 44. conceptacles, 44. collecting plants, 44. cells, 44. chloroplasts, 44. oögonium, 45. _platycarpus_, 45. antheridium, 45, 46. fertilization, 46. germination, 46.

_Fumariaceæ_. See "Fumitory."

Fumitory, 192.

_Funaria_, 93-99; Figs. 58-62. gross anatomy, 93, 94. protonema, 93. "flower," 94. structure of leaf, 94. chloroplasts, division of, 95. formation of starch in chloroplasts, 95. structure of stem, 96. root hairs, 96. buds, 96. antheridium spermatozoids, 96, 97. archegonium, 97. embryo, 98. capsule and spores, 98, 99. germination of spores, 99.

Fungi, culture of, 5, 54. true. See "_Mycomycetes_." alga. See "_Phycomycetes_."

Funiculus, 151, 175.

_Funkia_. See "Day lily."

_Galium_, 223; Fig. 124.

_Gamopetalæ_. See "_Sympetalæ_."

_Gaultheria_. See "Wintergreen."

_Gaylussacia_. See "Huckleberry."

_Geaster_, 84; Fig. 49.

Gentian, 218; Fig. 122.

Gentian violet, 4, 138, 231.

_Gentiana_, _-aceæ_. See "Gentian."

_Geranium_, _-aceæ_, 3, 171, 196; Fig. 107.

_Gerardia_, 217.

Germ cell. See "Egg cell."

_Gesneraceæ_, 218.

Ghost flower. See "Indian-pipe."

Gill, 83.

Ginger, 163.

_Gingko_, 142; Fig. 78.

_Gleditschia_. See "Honey locust."

_Gloxinia_, 218.

_Glumaceæ_, 153, 160; Fig. 87.

Glume, 162.

Glycerine, 4, 51, 55, 59, 67, 83, 98, 224, 231, 233.

_Gnetaceæ_. See "Joint fir."

Golden-rod, 224.

_Gonium_, 20.

Gooseberry, 203; Fig. 111.

Goose-foot, 184; Fig. 98.

_Gossypium_. See "Cotton."

Gourd, 221.

_Gramineæ_. See "Grass."

Grape, 171, 199; Fig. 109.

Grape fern, 116; Fig. 70.

_Graphis_, 75; Fig. 45.

Grass, 161, 225; Fig. 87.

Gray moss. See "_Tillandsia_."

Green-brier, 154.

Green-felt. See "_Vaucheria_."

Green monad, 12, 19.

Green slime, 21, 22; Fig. 11.

Ground pine, 123; Fig. 73.

Ground tissue, 110, 111, 113, 124, 137, 177, 178.

_Gruinales_, 196.

Guard cell, 113, 135, 150.

Gulf weed. See "_Sargassum_."

Gum. See "_Eucalyptus_."

_Gymnocarpæ_, 84.

Gymnosperm, 129, 141.

_Gymnosporangium_, 79-81; Fig. 47. cedar apples, 79. spores, 80.

_Gynandræ_, 153, 164.

Gynœcium, 148, 167.

Gynostemium. See "Column."

_Habenaria_, 166, 227; Fig. 90.

Hæmatoxylin, 233.

Hair, 8, 177.

_Haloragidaceæ_, 206.

Hazel, 182, 183, 225; Fig. 97.

Head, 181.

Heath, 211.

_Helobiæ_, 153, 167.

_Hemerocallis_. See "Day lily."

_Hemi-angiocarpæ_, 84.

Hemlock, 142; Fig. 78.

Hemp, 183.

_Hepaticæ_. See "Liverwort."

Hermaphrodite, 199.

Heterocyst, 17.

Heterostylism, 228.

_Hibiscus_, 195.

Hickory, 170, 183.

Holly, 199.

Hollyhock, 195.

Honey locust, 209.

Honeysuckle, 170, 172, 181, 223; Fig. 124.

Hop, 171, 181; Fig. 97.

Horned pond-weed, 224.

Horse-chestnut, 170, 199.

Horse-tail, 116-120. field, 120-122; Fig. 72. stems and tubers, 120. fertile branches, 120. leaves, 121. cone, 121. stem, 121. sporangia and spores, 121. sterile branches, 121. histology of stem, 121. of sporangia, 122. spores, 122. germination, prothallium, 122.

Hound's-tongue, 215; Fig. 119.

_Houstonia_, 223; Fig. 124.

_Hoya_. See "Wax-plant."

Huckleberry, 181, 211; Fig. 116.

Humming-bird, 226.

Hyacinth, 146.

_Hydnum_, 84; Fig. 51.

_Hydrangea_, _-geæ_, 202; Fig. 111.

_Hydrocharideæ_, 167.

Hydrogen, 2, 95.

_Hydropeltidinæ_, 189.

_Hydrophyllum_, _-aceæ_. See "Water-leaf."

_Hypericum_, _-aceæ_. See "St. John's-wort."

_Ilex_. See "Holly."

_Impatiens_. See "Jewel-weed," "Balsam."

India-rubber, 200.

Indian-pipe, 144, 210; Fig. 79.

Indian turnip. See "_Arisæma_."

Indusium, 118.

Inflorescence, 157.

Integument, 133, 144, 151, 180.

Intercellular space, 124, 135, 150.

Internode, 39.

Iodine, 4, 22, 31.

_Ipomœa_, 213.

_Iridaceæ_, 156.

Iris, 154, 156; Fig. 84.

Irish moss, 49.

_Isocarpæ_, 210, 212.

_Isoetes_. See "Quill-wort."

_Iulifloræ_, 181.

Ivy, 202.

Jack-in-the-pulpit. See "_Arisæma_."

Jasmine, 218.

_Jeffersonia_. See "Twin-leaf."

Jewel-weed, 197; Fig. 107.

Joint fir, 140, 142.

_Juncagineæ_, 167.

_Juncus_. See "Rush."

_Jungermanniaceæ_, 92; Fig. 57.

_Kalmia_. See "Mountain laurel."

Karyokinesis, 233.

Keel, 208.

Kelp. See "_Laminaria_." giant. See "_Macrocystis_."

Knotgrass. See "_Polygonum_."

Labellum. See "Lip."

_Labiatæ_. See "Mint."

_Labiatifloræ_, 215.

Lady's-slipper, 164, 166, 198; Fig. 90.

Lamella, 83.

_Laminaria_, 45, 47; Fig. 28.

_Lamium_. See "Dead nettle."

Larch. See "Tamarack."

_Larix_. See "Tamarack."

Larkspur, 186, 227; Fig. 99.

Latex, 191.

Laurel, 188.

_Laurineæ_. See "Laurel."

Lavender, 215.

Leaf-green. See "Chlorophyll."

Leaf tendril, 171.

Leaf thorn, 172.

_Leguminosæ_, 207.

_Lemanea_, 53; Fig. 31.

_Lemna_. See "Duck-weed."

Lemon, 198.

_Lentibulariaceæ_, 217.

Lettuce, 223.

_Lichenes_, 73; Figs. 44, 45.

Ligula, 127.

_Ligulatæ_, 125.

Lilac, 170, 181, 218.

_Liliaceæ_, 155.

_Liliifloræ_, 153, 155; Fig. 83.

_Lilium_. See "Lily."

Lily, 146, 155.

Lily-of-the-valley, 155.

Lime. See "Linden."

Linden, 195; Fig. 106.

Linear, 159.

_Linum_, _-aceæ_. See "Flax."

Lip, 165.

_Liriodendron_. See "Tulip-tree."

_Lithospermum_. See "Puccoon."

Liverwort, 86. classification of, 91. horned. See "_Anthoceroteæ_." giant, 91; Fig. 57.

Lizard-tail, 181, 183; Fig. 97.

_Lobelia_, _-aceæ_. 221; Fig. 123.

_Loganieæ_, 219.

_Lonicera_. See "Honeysuckle."

Loosestrife. See "_Lythrum_." swamp. See "Nesæa."

Lotus. See "_Nelumbo_."

_Lychnis_, 185.

_Lycoperdon_, 84; Fig. 49.

_Lycopersicum_. See "Tomato."

_Lycopodiaceæ_. See "Ground pine."

_Lycopodinæ_. See "Club moss."

_Lycopodium_, 123. _dendroideum_, 123, 124; Fig. 73. stem and leaves, 123. cones and sporangia, 123. gross anatomy, 123. histology, 124. spores, 124.

_Lysimachia_. See "Moneywort."

_Lythrum_, _-aceæ_, 206, 228.

Mace, 189.

_Macrocystis_, 48.

Macrospore, 126, 127, 128, 143.

_Madotheca_, 86-90; Figs. 52-56. gross anatomy, 86-88. male and female plants, 87, 88. histology of leaf and stem, 88. antheridium, 88, 89. archegonium, 89, 90. embryo, 90. spores and elaters, 90.

Magnesium, 2.

_Magnolia_, _-aceæ_, 186.

Maiden-hair fern, 109-115; Figs. 67-69. general structure, 109. gross anatomy of stem, 110. histology of stem, 110, 111. gross anatomy of leaf, 111. histology of leaf, 111, 112. sporangia, 113, 114. root, 114, 115. apical growth of root, 115.

Mallow, 171, 195; Fig. 106.

_Malva_, _-aceæ_. See "Mallow."

_Mamillaria_, Fig. 112.

Mandrake. See "May-apple."

Maple, 199; Fig. 108.

_Maranta_. See "Arrowroot."

_Marattiaceæ_. See "Ringless ferns."

_Marchantia_, 91; Fig. 57. breathing-pores, 91. sexual organs, 91. buds, 91.

_Marchantiaceæ_, 91.

_Marsilia_, 118; Fig. 71.

_Martynia_, 218.

_Matthiola_. See "Stock."

May-apple, 187; Fig. 101.

May-weed, 223; Fig. 125.

_Medeola_, 155; Fig. 83.

Medullary ray, 130, 137.

_Melampsora_, 81.

_Melastomaceæ_, 206.

Melon, 221.

_Menispermum_, _-eæ_. See "Moon-seed."

_Menyanthes_. See "Buck-bean."

_Mesocarpus_, 33; Fig. 19.

Mesophyll, 135.

Methyl-violet, 4, 233.

Micropyle, 180.

Microsome, 231.

Microspore, 126, 128, 131, 138.

Mignonette, 192; Fig. 104.

Mildew. See "_Peronospora_," "_Phytophthora_," "_Perisporiaceæ_."

Milk-weed, 220; Fig. 122.

Milkwort, 199.

_Mimosa_. See "Sensitive-plant."

_Mimosaceæ_, 209, 210.

_Mimulus_, 217.

Mint, 181, 215.

_Mirabilis_. See "Four-o'clock."

Mistletoe, 224.

_Mitella_. See "Bishop's cap."

_Mitchella_. See "Partridge-berry."

Mitre-wort. See "Bishop's cap."

Mock-orange. See "_Syringa_."

Moneywort, 212; Fig. 117.

Monocotyledon, 146, 153, 225, 229.

_Monotropa_. See "Indian-pipe," "Pine-sap."

_Monotropeæ_, 210.

Moon-seed, 188; Fig. 101.

Moosewood, 206; Fig. 113.

_Morchella_. See "Morel."

Morel, 73.

Morning-glory, 171, 213; Fig. 118.

Morphology, 3.

Moss, 5, 86. true, 93. common. See "_Bryaceæ_." peat. See "_Sphagnaceæ_."

Moth, 229.

Mould, black. See "_Mucorini_." blue. See "_Penicillium_." herbarium. See "_Eurotium_." insect. See "_Entomophthoreæ_." water. See "_Saprolegnia_."

Mountain-fringe, 192.

Mountain-laurel, 210; Fig. 116.

_Mucor_, 55. mucedo, 56; Fig. 32.

_Mucor stolonifer_, 55-56. general structure, 55. structure of filaments, 55. spore cases, 55. sexual spores, 56.

_Mucorini_, 54.

Mulberry, 183.

Mullein, 217; Fig. 120.

_Musa_, _-aceæ_. See "Banana."

_Musci_. See "True mosses."

Mushroom, 82.

Mustard, 192.

_Mycomycetes_. See "True fungi."

_Myosotis_. See "Forget-me-not."

_Myristica_, _-ineæ_. See "Nutmeg."

_Myrtifloræ_, 205.

Myrtle, 205, 206.

_Myrtus_. See "Myrtle."

_Myxomycetes_. See "Slime-mould."

_Naias_. See "Pond-weed."

_Naiadeæ_, 159.

Narcissus, 146.

Nasturtium, 197, 227.

_Navicula_, 42; Fig. 24.

Nectar, 225.

Nectary, 186.

Nelumbo, 189, 190; Fig. 101.

_Nelumbieæ_, 190.

_Nemophila_, 214.

_Nepenthes_, _-eæ_. See "Pitcher plant."

_Nesæa_, 206.

Nettle. See "_Urticinæ_."

_Nicotiana_. See "Tobacco."

Night-blooming cereus, 204.

Nightshade, 215; Fig. 119.

_Nitella_, 40.

_Nitelleæ_, 40.

Node, 39.

Nucleus, 7, 31, 231.

Nuclear division, 7, 31, 231; Figs. 127, 128.

Nucleolus, 7, 231.

Nutmeg, 188.

_Nyctagineæ_, 183.

_Nymphæa_, 189; Fig. 101.

_Nymphæaceæ_, 190.

Oak, 183, 225; Fig. 97.

_Œdogonium_, 26-28; Fig. 16. reproduction, 27. fertilization, 28. resting spores, 28.

_Œnothera_. See "Evening primrose."

Oil-channel, 202.

_Oleaceæ_. See "Olive."

Oleander, 219.

Olive, 218.

_Onagraceæ_, 206.

_Onoclea_, 104; Fig. 70.

Oögonium, 27, 36, 39, 45, 59, 62.

Oöphyte, 109.

Opium--opium poppy, 191.

_Ophioglosseæ_. See "Adder-tongue."

_Ophioglossum_, 116.

_Opuntia_. See "Prickly pear."

_Opuntieæ_, 203.

Orange, 198.

Orchid, 164, 166, 227; Figs. 89, 90.

_Orchideæ_, 164.

_Orchis_, 227; Fig. 89.

Organic bodies, 1.

Origanum oil, 234.

_Oscillaria_, 15, 16; Fig. 6. movements, 15. color, 16. structure and reproduction, 16.

_Osmunda_. See "Flowering-fern."

Ostrich-fern, 104-109. germination of spores, 104. prothallium, 104, 105. archegonium, 105, 106. antheridium and spermatozoids, 106. fertilization, 107. embryo and young plant, 107, 108. comparison with sporogonium of bryophytes, 109.

Ovary, 129, 148, 156, 202.

Ovule, 129, 131, 144, 148, 151, 179.

_Oxalis_. See "Wood-sorrel."

_Oxydendrum_, 211; Fig. 116.

Oxygen, 2, 95.

Palea, 161.

Palisade parenchyma, 178.

Palm, 157. date, 159. coco, 159.

_Palmæ_. See "Palm."

Palmate, 171.

Palmetto, 159.

_Pandaneæ_, 159.

_Papaveraceæ_. See "Poppy."

Papaw, 186; Fig. 100.

_Papilionaceæ_, 208.

Pappus, 223.

_Papyrus_, 161.

Paranucleus, 231.

Parasite, 54.

Parenchyma. See "Soft tissue."

_Parmelia_, 73, 75; Fig. 44.

Partridge-berry, 223, 228.

_Passiflora_. See "Passion-flower."

_Passiflorinæ_, 205.

Passion-flower, 204; Fig. 112.

Pea, 207, 208; Fig. 115.

Peach, 206.

Pear, 206.

_Pediastrum_, 23; Fig. 11.

_Pelargonium_, 197.

Peltate, 190.

_Peltigera_, 75; Fig. 45.

_Penicillium_, 71; Fig. 42.

Pepper, 183.

Perianth. See "Perigone."

Periblem, 176.

Perigone, 143, 148, 151, 170.

Perisperm, 163.

_Perisporiaceæ_, 66.

Periwinkle, 219.

_Peronospora_, 60; Fig. 35.

_Peronosporeæ_, 57.

Persimmon, 212; Fig. 117.

Petal, 148, 174, 179.

Petiole, 173.

Petunia, 215; Fig. 119.

_Peziza_, 73; Fig. 43.

_Phacelia_, 214.

_Phæophyceæ_. See "Brown algæ."

Phænogam. See "Spermaphyte."

_Phascum_, _-aceæ_, 99, 101; Fig. 65.

_Philadelphus_. See "Syringa."

Phloem, 110, 124, 135, 137, 150, 173, 176.

_Phlox_, 214; Fig. 118.

_Phœnix dactylifera_. See "Date-palm."

Phosphorus, 2.

_Phragmidium_, 81; Fig. 47.

_Physarum_, 14.

_Physianthus_, 220.

Physiology, 3.

_Phytolacca_, _-aceæ_. See "Poke-weed."

_Phytophthora_, 60.

Pickerel-weed, 156, 228; Fig. 84.

Picric acid, 156, 233.

Pig-weed. See "Amaranth."

Pine, 9, 10, 129, 142.

Pineapple, 156.

Pine-sap, 210; Fig. 116.

_Pinguicula_, 218.

Pink, 181, 185; Fig. 97.

Pink-root, 218; Fig. 122.

Pinnate (leaf), 159. veined, 171.

_Pinnularia_, 42; Fig. 24.

_Pinus sylvestris_. See "Scotch pine."

_Piper_. See "Pepper."

_Piperineæ_, 183.

Pistil, 143, 145, 174.

Pitcher-plant, 194, 195; Fig. 105.

Pith, 130, 174, 177.

Placenta, 148, 179.

Plane, 183.

_Plantago_, _-ineæ_. See "Plantain."

Plantain, 223, 225; Fig. 121.

Plasmodium, 12.

_Plataneæ_. See "Plane."

_Platanus_. See "Sycamore."

Plerome, 176.

Plum, 207.

_Plumbago_, _-ineæ_, 212.

Pod, 156.

_Podophyllum_. See "May-apple."

_Podosphæra_, 66-70; Fig. 39. general structure, 66. structure of filaments, 68. suckers, 68. conidia, 68. sexual organs, 68. spore fruit, 68, 69. spore sac, 69.

_Pogonia_, 166.

_Poinsettia_, 199.

Poison-dogwood, 198.

Poison-hemlock, 202.

Poison-ivy, 171, 198.

Poke-weed, 185; Fig. 97.

_Polemonium_, _-aceæ_, 214; Fig. 118.

Pollinium, 165.

_Polycarpæ_, 185.

_Polygala_, _-aceæ_. See "Milkwort."

_Polygonatum_. See "Solomon's Seal."

_Polygonum_, _-aceæ_, 184; Fig. 98.

_Polysiphonia_, 52; Fig. 29.

Pomegranate, 206.

Pond-scum, 22, 29, 30.

Pond-weed, 159; Fig. 86.

_Pontederia_. See "Pickerel-weed."

Poplar, 181, 183.

Poppy, 191.

_Portulaca_, _-aceæ_. See "Purslane."

Potash (caustic), 4, 5, 59, 67, 75, 97, 106, 111, 151, 176, 179, 180.

Potassium, 2.

Potato, 215.

Potato-fungus. See "_Phytophthora_."

_Potentilla_. See "Cinquefoil."

_Potomogeton_. See "Pond-weed."

Prickly-ash, 198.

Prickly fungus. See "_Hydnum_."

Prickly-pear, 204.

Prickly-poppy. See "_Argemone_."

Primrose, 211.

_Primula_, _-aceæ_. See "Primrose."

Prince's-pine, 210; Fig. 116.

Procarp, 51.

_Proteaceæ_, 205.

Prothallium, 102, 103, 114, 122, 125, 133, 144, 177.

_Protococcus_, _-aceæ_, 22, 74; Fig. 11.

Protophyte, 11.

Protoplasm, 7. movements of, 7.

Pteridophyte, 102, 153.

_Puccinia_, 81; Fig. 47. See also "Wheat-rust."

Puccoon, 215.

Puff-ball. See "_Lycoperdon_."

Purslane, 185.

Putty-root. See "_Aplectrum_."

Pyrenoid, 25, 31.

_Pyrenomycetes_, 76.

_Pyrola_, _-aceæ_, 210.

Quince, 170.

Quill-wort, 125, 126; Fig. 74.

Raceme, 174.

Radial fibro-vascular bundles, 138, 176.

Radish, 192.

_Ranunculus_, _-aceæ_. See "Buttercup."

Raspberry, 207.

Ray-flower, 223.

Receptacle, 167, 207, 223.

Receptive spot, 106.

Red algæ, 21, 49, 52, 53; Figs. 29-31.

Red-bud, 209; Fig. 115.

Red cedar, 79, 131, 141; Fig. 78.

Red-wood, 142.

Reference-books, 235-236.

_Reseda_, _-aceæ_. See "Mignonette."

Resin, 130.

Resin-duct, 130, 135, 137.

Resting-spore, 28, 32, 37, 57.

Rheumatism-root. See "Twin-leaf."

_Rhexia_, 206.

_Rhizocarpeæ_. See "Water-fern."

Rhizoid. See "Root-hair."

Rhizome. See "Root-stock."

_Rhododendron_, 210; Fig. 116.

_Rhodophyceæ_. See "Red algæ."

_Rhodoraceæ_, 211.

_Rhœadinæ_, 190.

_Rhus_. See "Sumach." _cotinus_. See "Smoke-tree." _toxicodendron_. See "Poison-ivy." _venenata_. See "Poison-dogwood."

_Ribes_, _-ieæ_, 203; Fig. 111.

_Ricciaceæ_, 91; Fig. 57.

_Richardia_. See "Calla."

_Ricinus_. See "Castor-bean."

Ringless-fern, 116.

Rock-rose, 195.

Rock-weed. See "_Fucus_."

Root, 102, 104, 114, 173.

Root-cap, 115, 175.

Root-hair, 38, 87, 91, 96, 104, 135.

Root-stock, 154, 172.

_Rosa_, _-aceæ_. See "Rose."

Rose, 181, 206; Fig. 114.

_Rosifloræ_, 206.

_Rubiaceæ_, 223.

Rush, 154, 225; Fig. 83.

Rust, white. See "_Cystopus_." red. See "_Uredineæ_." black. See "_Uredineæ_."

_Sabal_. See "Palmetto."

_Sabbatia_. See "Centaury."

_Saccharomycetes_. See "Yeast."

Sac fungi. See "_Ascomycetes_."

Safranine, 233.

Sage, 215; Fig. 120.

_Salicineæ_, 183.

_Salix_. See "Willow."

_Salvinia_, 118.

_Sambucus_. See "Elder."

_Sanguinaria_. See "Blood-root."

_Sapindaceæ_, 199.

_Saprolegnia_, _-aceæ_, 60-62; Fig. 36. zoöspores, 62. resting spores, 62. antheridium, 62.

_Sargassum_, 48; Fig. 28.

_Sarracenia_, _-aceæ_. See "Pitcher-plant."

Sassafras, 188.

_Saururus_. See "Lizard-tail."

Saxifrage, 202.

_Saxifraginæ_, 202.

_Scabiosa_. See "Scabious."

Scabious, 224.

Scalariform, 110.

Scale-leaves, 170.

_Scenedesmus_, 24; Fig. 11.

_Schizomycetes_. See "_Bacteria_."

Schizophytes, 12, 14.

Schlerenchyma. See "Stony tissue."

_Schrankia_. See "Sensitive-brier."

_Scilla_, 151.

_Scirpus_. See "Bulrush."

_Scitamineæ_, 153, 162.

Scotch pine, 129-140; Figs. 75-77. stems and branches, 129. leaves, 129, 130. gross anatomy of stem, 130. growth-rings, 130. roots, 131. sporangia, 131. cones, 132. macrospores and prothallium, 133. ripe cone and seeds, 133. germination, 134. young plant, 134. histology of leaf, 135. of stem, 136-138. of root, 138. microsporangium and pollen spores, 138, 139. archegonium, 140. fertilization, 140.

Scouring-rush, 122.

_Scrophularia_, _-ineæ_. See "Figwort."

Sea-lettuce, 26; Fig. 15.

Sea-rosemary, 212.

Sea-weed (brown). See "Brown algæ." (red). See "Red algæ."

Sedge, 161; Fig. 87.

_Sedum_. See "Stonecrop."

Seed, 128, 133, 145, 150.

Seed-plant. See "Spermaphyte."

_Selaginella_, _-eæ_. See "Smaller club-moss."

Sensitive-brier, 209; Fig. 115.

Sensitive-plant, 209.

Sepal, 148, 150, 174, 179.

_Sequoia_. See "Red-wood."

Sessile leaf, 170.

_Shepherdia_, 206.

Shepherd's-purse, 173-180; Figs. 93-95. gross anatomy of stem, 173. leaf, 124, 173. root, 173. branches, 174. flower, 174, 175. fruit and seed, 175. histology of root, 175, 176. stem, 177. leaf, 177, 178. development of flower, 179. ovule, 179. embryo, 180.

Shooting-star, 212; Fig. 117.

Sieve-tube, 111, 137.

_Silene_. See "Catch-fly."

Silicon, 2.

Simple leaf, 170.

_Siphoneæ_, 22, 34.

_Sisyrinchium_. See "Blue-eyed grass."

Skunk cabbage, 157.

Slime mould, 12, 14; Fig. 5. plasmodium, 12. movements, 13. feeding, 13. spore-cases, 13. spores, 13. germination of spores, 14.

Smart-weed. See "_Polygonum_."

_Smilaceæ_, 155.

Smoke-tree, 198.

Smut, 64, 65.

Smut-corn. See "_Ustillago_."

Snowberry, 223.

Soft-tissue, 112.

_Solanum_, _-eæ_, 215.

Solomon's Seal, 154; Fig. 83.

Soredium, 74.

Sorus, 118.

_Spadicifloræ_, 153, 157.

Spadix, 157.

Spanish bayonet. See "_Yucca_."

_Sparganium_. See "Bur-reed."

Speedwell. See "_Veronica_."

Spermaphyte, 128-129.

Spermatozoid, 28, 36, 40, 46, 51, 89, 96, 106, 122.

Spermagonium, 79, 80.

_Sphagnum_, _-aceæ_, 99, 100. sporogonium, 100. leaf, 100.

Spice-bush, 188.

Spiderwort, 6, 151, 157; Fig. 85.

_Spigelia_. See "Pink-root."

Spike, 181.

Spikenard, 202; Fig. 110.

Spinach, 184.

Spindle-tree, 199; Fig. 109.

_Spirogyra_, 30-32; Fig. 18. structure of cells, 30. starch, 31. cell-division, 31. sexual reproduction, 32.

Sporangium, 55, 62, 113, 121, 122, 131, 148, 151, 179.

Spore-case. See "Sporangium."

Spore-fruit, 51, 66, 69, 70, 73, 83.

Spore-sac. See "Ascus."

Sporocarp. See "Spore-fruit."

Sporogonium, 87, 90, 102, 123.

Sporophyll, 128, 131, 148.

Sporophyte, 109.

Spring-beauty, 185; Fig. 98.

Spruce, 142.

Spurge. See "_Euphorbia_."

Squash, 221.

Staining agents, 4, 231, 233.

Stamen, 128, 143, 148, 174, 179.

Standard, 207.

_Staphylea_. See "Bladder-nut."

Starch, 31, 95, 152.

_Statice_. See "Sea-rosemary."

_Stellaria_. See "Chick-weed."

_Stemonitis_, 13; Fig. 5.

_Sticta_, 75; Fig. 45.

_Stigeoclonium_, 26; Fig. 14.

Stigma, 145, 148, 175, 179.

St. John's-wort, 195; Fig. 105.

Stock, 192.

Stoma. See "Breathing-pore."

Stonecrop, 202; Fig. 113.

Stone-fruit, 206.

Stone-wort. See "_Characeæ_."

Stony-tissue, 110.

Stramonium, 215.

Strawberry, 171, 202, 206; Fig. 113.

Style, 148, 175, 179.

_Stylophorum_, 187; Fig. 103.

Sugar, 8, 145.

Sulphur, 2.

Sumach, 198; Fig. 108.

Sun-dew, 192, 193; Fig. 104.

Sunflower, 224.

Suspensor, 180.

Sweet-flag, 157.

Sweet-potato, 214.

Sweet-scented shrub. See "_Calycanthus_."

Sweet-william, 185.

Sycamore, 183.

_Sympetalæ_, 210.

_Symphoricarpus_. See "Snowberry."

_Symplocarpus_. See "Skunk-cabbage."

Synergidæ, 144.

_Syringa_, 199; Fig. 111. See also "Lilac."

Tamarack, 142.

Tap-root, 131, 173.

_Taraxacum_. See "Dandelion."

_Taxodium_. See "Cypress."

_Taxus_. See "Yew."

Teasel, 224; Fig. 124.

_Tecoma_. See "Trumpet-creeper."

Teleuto-spore, 80, 81.

Tendril, 171.

_Terebinthinæ_, 198.

Tetraspore, 51, 52.

Thistle, 173, 223; Fig. 125.

Thorn, 172.

Thyme, 215.

_Thymeleaceæ_, 206.

_Thymelinæ_, 206.

_Tilia_, _-aceæ_. See "Linden."

_Tillandsia_, 156; Fig. 84.

Tissue, 8.

Tissue system, 115.

Toadstool, 82.

Tobacco, 215.

_Tolypella_, 40.

Tomato, 215.

Touch-me-not. See "Jewel-weed."

Tracheary tissue, 110, 121, 177.

Tracheid, 110, 138.

_Tradescantia_. See "Spiderwort."

Trailing arbutus, 211.

_Tremella_, 81; Fig. 51.

_Trichia_, 13, 14; Fig. 5.

Trichogyne, 51.

_Tricoccæ_, 199.

_Triglochin_. See "Arrow-grass."

_Trillium_, 146, 154, 155; Fig. 83.

_Triphragmium_, 81.

_Tropæolum_. See "Nasturtium."

Trumpet-creeper.

Tuber, 120, 153, 172.

_Tubifloræ_, 213.

Tulip, 146.

Tulip-tree, 187; Fig. 100.

Turnip, 192.

Twin-leaf, 187; Fig. 101.

_Typha_, _-aceæ_. See "Cat-tail."

_Ulmaceæ_. See "Elm."

_Ulva_. See "Sea-lettuce."

_Umbelliferæ_. See "Umbel-wort."

Umbel-wort, 202.

_Umbellifloræ_, 202.

_Uredineæ_, 77.

_Uromyces_, 81; Fig. 47.

_Urticinæ_, 183.

_Usnea_, 75; Fig. 45.

_Ustillagineæ_. See "Smut."

_Ustillago_, 65; Fig. 38.

_Utricularia_. See "Bladder-weed."

_Uvularia_. See "Bellwort."

_Vaccinium_. See "Cranberry."

Vacuole, 8.

Valerian, 224; Fig. 124.

_Valeriana_, _-eæ_. See "Valerian."

_Vallisneria_. See "Eel-grass."

_Vanilla_, 166.

_Vaucheria_, 34-37; Figs. 21, 22. structure of plant, 35. _racemosa_, 35. non-sexual reproduction, 36. sexual organs, 36. fertilization, 36. resting spores, 37.

Venus's fly-trap, 192.

_Verbascum_. See "Mullein."

_Verbena_, _-aceæ_, 218; Fig. 121.

_Veronica_, 217; Fig. 120.

Vervain. See "_Verbena_."

Vessel, 121, 135, 150, 175, 177.

_Viburnum_, 223; Fig. 124.

_Victoria regia_, 190.

_Vinca_. See "Periwinkle."

Vine, 199.

Violet, 192; Fig. 104.

_Viola_, _-aceæ_. See "Violet."

Virginia creeper, 171, 199.

_Vitis_. See "Grape."

_Vitaceæ_. See "Vine."

_Volvox_, 12, 20; Fig. 10.

_Volvocineæ_, 12, 19.

Wall-flower, 192.

Walnut, 183.

Wandering-Jew, 157.

Water fern, 117.

Water-leaf, 214; Fig. 118.

Water-lily. See "_Nymphæa_," "_Castalia_."

Water-milfoil, 206; Fig. 113.

Water mould. See "_Saprolegnia_."

Water net, 24; Fig. 11.

Water-plantain, 167.

Water-shield, 190.

Water-starwort, 200.

Wax-plant, 220.

Wheat, 78.

Wheat rust, 78, 81; Fig. 47.

_Whitlavia_, 214.

Wild ginger, 224; Fig. 126.

Wild onion, 230.

Wild parsnip, 202.

Willow, 181-183; Fig. 96.

Willow-herb, 206, 226; Fig. 113.

Wing (of papilionaceous flower), 208.

Wintergreen, 211.

_Wolffia_, 159.

Wood. See "Xylem."

Wood-sorrel, 197; Fig. 107.

Xylem, 110, 124, 135, 150, 173, 176.

Yam, 154.

Yeast, 63, 64; Fig. 37. cause of fermentation, 63. reproduction, 64. systematic position, 64.

Yew, 141.

_Yucca_, 153.

_Zanthoxylum_. See "Prickly ash."

_Zingiber_, _-aceæ_. See "Ginger."

Zoölogy, 2.

Zoöspore, 25, 37, 58, 62.

_Zygnema_, 33; Fig. 19.

Zygomorphy, Zygomorphic, 164, 215, 226.

NATURAL SCIENCE.

_Elements of Physics._

A Text-book for High Schools and Academies. By ALFRED P. GAGE, A.M., Instructor in Physics in the English High School, Boston. 12mo. 424 pages. Mailing Price, $1.25; Introduction, $1.12; Allowance for old book, 35 cents.

This treatise is based upon _the doctrine of the conservation of energy_, which is made prominent throughout the work. But the leading feature of the book--one that distinguishes it from all others--is, that it is strictly _experiment-teaching_ in its method; _i.e._, it leads the pupil to "read nature in the language of experiment." So far as practicable, the following plan is adopted: The pupil is expected to accept as _fact_ only that which he has seen or learned by personal investigation. He himself performs the larger portion of the experiments with _simple_ and _inexpensive_ apparatus, such as, in a majority of cases, is in his power to construct with the aid of directions given in the book. The experiments given are rather of the nature of _questions_ than of illustrations, and _precede_ the statements of principles and laws. Definitions and laws are not given until the pupil has acquired a knowledge of his subject sufficient to enable him to construct them for himself. The aim of the book is to lead the pupil _to observe and to think_.

C. F. EMERSON, _Prof. of Physics, Dartmouth College_: It takes up the subject on the right plan, and presents it in a clear, yet scientific, way.

WM. NOETLING, _Prof. of Rhetoric, Theory and Practice of Teaching, State Normal School, Bloomsburg, Pa._: Every page of the book shows that the author is a _real_ teacher and that he knows how to make pupils think. I know of no other work on the subject of which this treats that I can so unreservedly recommend to all wide-awake teachers as this.

B. F. WRIGHT, _Supt. of Public Schools, St. Paul, Minn._: I like it better than any text-book on physics I have seen.

O. H. ROBERTS, _Prin. of High School, San Jose, Cal._: Gage's Physics is giving great satisfaction.

_Introduction to Physical Science._

By A. P. GAGE, Instructor in Physics in the English High School, Boston, Mass., and Author of _Elements of Physics_, etc. 12mo. Cloth. viii + 353 pages. With a chart of colors and spectra. Mailing Price, $1.10; for introduction, $1.00; allowance for an old book in exchange, 30 cents.

The great and constantly increasing popularity of Gage's _Elements of Physics_ has created a demand for an equally good but easier book, on the same plan, suitable for schools that can give but a limited time to the study. The _Introduction to Physical Science_ has been prepared to supply this demand.

ACCURACY is the prime requisite in scientific text-books. A false statement is not less false because it is plausible, nor an inconclusive experiment more satisfactory because it is diverting. In books of entertainment, such things may be permissible; but in a text-book, the first essentials are correctness and accuracy. It is believed that the _Introduction_ will stand the closest expert scrutiny. Especial care has been taken to restrict the use of scientific terms, such as _force_, _energy_, _power_, etc., to their proper significations. Terms like _sound_, _light_, _color_, etc., which have commonly been applied to both the effect and the agent producing the effect have been rescued from this ambiguity.

RECENT ADVANCES in physics have been faithfully recorded, and the relative practical importance of the various topics has been taken into account. Among the new features are a full treatment of electric lighting, and descriptions of storage batteries, methods of transmitting electric energy, simple and easy methods of making electrical measurements with inexpensive apparatus, the compound steam-engine, etc. Static electricity, which is now generally regarded as of comparatively little importance, is treated briefly; while dynamic electricity, the most potent and promising physical element of our modern civilization, is placed in the clearest light of our present knowledge.

In INTEREST AND AVAILABILITY the _Introduction_ will, it is believed, be found no less satisfactory. The wide use of the _Elements_ under the most varied conditions, and, in particular, the author's own experience in teaching it, have shown how to improve where improvement was possible. The style will be found suited to the grades that will use the book. The experiments are varied, interesting, clear, and of practical significance, as well as simple in manipulation and ample in number. Certain subjects that are justly considered difficult and obscure have been omitted; as, for instance, certain laws relating to the pressure of gases and the polarization of light. The _Introduction_ is even more fully illustrated than the _Elements_.

IN GENERAL. The _Introduction_, like the _Elements_, has this distinct and distinctive aim,--to elucidate science, instead of "popularizing" it; to make it liked for its own sake, rather than for its gilding and coating; and, while teaching the facts, to impart the spirit of science,--that is to say, the spirit of our civilization and progress.

GEORGE E. GAY, _Prin. of High School, Malden, Mass._: With the matter, both the topics and their presentation, I am better pleased than with any other Physics I have seen.

R. H. PERKINS, _Supt. of Schools, Chicopee, Mass._: I have no doubt we can adopt it as early as next month, and use the same to great advantage in our schools. (_Feb. 6, 1888._)

MARY E. HILL, _Teacher of Physics, Northfield Seminary, Mass._: I like the truly scientific method and the clearness with which the subject is presented. It seems to me admirably adapted to the grade of work for which it is designed. (_Mar. 5, '88._)

JOHN PICKARD, _Prin. of Portsmouth High School, N.H._: I like it exceedingly. It is clear, straightforward, practical, and not too heavy.

EZRA BRAINERD, _Pres. and Prof. of Physics, Middlebury College, Vt._: I have looked it over carefully, and regard it as a much better book for high schools than the former work. (_Feb. 6, 1888._)

JAMES A. DE BOER, _Prin. of High School, Montpelier, Vt._: I have not only examined, but studied it, and consider it superior as a text-book to any other I have seen. (_Feb. 10, '88._)

E. B. ROSA, _Teacher of Physics, English and Classical School, Providence, R.I._: I think it the best thing in that grade published, and intend to use it another year. (_Feb. 23, '88._)

G. H. PATTERSON, _Prin. and Prof. of Physics, Berkeley Sch., Providence, R.I._: A very practical book by a practical teacher. (_Feb. 2, 1888._)

GEORGE E. BEERS, _Prin. of Evening High School, Bridgeport, Conn._: The more I see of Professor Gage's books, the better I like them. They are popular, and at the same time scientific, plain and simple, full and complete. (_Feb. 18, 1888._)

ARTHUR B. CHAFFEE, _Prof. in Franklin College, Ind._: I am very much pleased with the new book. It will suit the average class better than the old edition.

W. D. KERLIN, _Supt. of Public Schools, New Castle, Ind._: I find that it is the best adapted to the work which we wish to do in our high school of any book brought to my notice.

C. A. BRYANT, _Supt. of Schools, Paris, Tex._: It is just the book for high schools. I shall use it next year.

_Introduction to Chemical Science._

By R. P. WILLIAMS, Instructor in Chemistry in the English High School, Boston. 12mo. Cloth. 216 pages. Mailing Price, 90 cents; for introduction, 80 cents; Allowance for old book in exchange, 25 cents.

In a word, this is a working chemistry--brief but adequate. Attention is invited to a few special features:--

1. This book is characterized by directness of treatment, by the selection, so far as possible, of the most interesting and practical matter, and by the omission of what is unessential.

2. Great care has been exercised to combine clearness with accuracy of statement, both of theories and of facts, and to make the explanations both lucid and concise.

3. The three great classes of chemical compounds--acids, bases, and salts--are given more than usual prominence, and the arrangement and treatment of the subject-matter relating to them is believed to be a feature of special merit.

4. The most important experiments and those best illustrating the subjects to which they relate, have been selected; but the modes of experimentation are so simple that most of them can be performed by the average pupil without assistance from the teacher.

5. The necessary apparatus and chemicals are less expensive than those required for any other text-book equally comprehensive.

6. The special inductive feature of the work consists in calling attention, by query and suggestion, to the most important phenomena and inferences. This plan is consistently adhered to.

7. Though the method is an advanced one, it has been so simplified that pupils experience no difficulty, but rather an added interest, in following it; the author himself has successfully employed it in classes so large that the simplest and most practical plan has been a necessity.

8. The book is thought to be comprehensive enough for high schools and academies, and for a preparatory course in colleges and professional schools.

9. Those teachers in particular who have little time to prepare experiments for pupils, or whose experience in the laboratory has been limited, will find the simplicity of treatment and of experimentation well worth their careful consideration.

Those who try the book find its merits have not been overstated.

A. B. AUBERT, _Prof. of Chemistry, Maine State College, Orono, Me._: All the salient points are well explained, the theories are treated of with great simplicity; it seems as if every student might thoroughly understand the science of chemistry when taught from such a work.

H. T. FULLER, _Pres. of Polytechnic Institute, Worcester, Mass._: It is clear, concise, and suggests the most important and most significant experiments for illustration of general principles.

ALFRED S. ROE, _Prin. of High School, Worcester, Mass._: I am very much pleased with it. I think it the most practical book for actual work that I have seen.

FRANK M. GILLEY, _Science Teacher, High School, Chelsea, Mass._: I have examined the proof-sheets in connection with my class work, and after comparison with a large number of text-books, feel convinced that it is superior to any yet published.

G. S. FELLOWS, _Teacher of Chemistry, High School, Washington, D.C._: The author's method seems to us the ideal one. Not only are the theoretical parts rendered clear by experiments performed by the student himself, but there is a happy blending of theoretical and applied chemistry as commendable as it is unusual.

J. I. D. HINES, _Prof. of Chemistry, Cumberland University, Lebanon, Tenn._: I am very much pleased with it, and think it will give the student an admirable introduction to the science of chemistry.

HORACE PHILLIPS, _Prin. of High School, Elkhart, Ind._: My class has now used it three months. It proves the most satisfactory text-book in this branch that I have ever used. The cost of apparatus and material is very small.

O. S. WESCOTT, _Prin. North Division H. Sch., Chicago_: My chemistry professor says it is the most satisfactory thing he has seen, and hopes we may be able to have it in future.

_Laboratory Manual of General Chemistry._

By R. P. WILLIAMS, Instructor in Chemistry, English High School, Boston, and author of _Introduction to Chemical Science_. 12mo. Boards. xvi + 200 pages. Mailing Price, 30 cents; for Introduction, 25 cents.

This Manual, prepared especially to accompany the author's _Introduction to Chemical Science_, but suitable for use with any text-book of chemistry, gives directions for performing one hundred of the more important experiments in general chemistry and metal analysis, with blanks and a model for the same, lists of apparatus and chemicals, etc.

The Manual is commended as well-designed, simple, convenient, and cheap,--a practical book that classes in chemistry need.

W. M. STINE, _Prof. of Chemistry, Ohio University, Athens, O._: It is a work that has my heartiest endorsement. I consider it thoroughly pedagogical in its principles, and its use must certainly give the student the greatest benefit from his chemical drill. (_Dec. 30, 1888._)

_Young's General Astronomy._

A Text-book for colleges and technical schools. By CHARLES A. YOUNG, Ph.D., LL.D., Professor of Astronomy in the College of New Jersey, and author of _The Sun_, etc. 8vo. viii + 551 pages. Half-morocco. Illustrated with over 250 cuts and diagrams, and supplemented with the necessary tables. Introduction Price, $2.25. Allowance for an old book in exchange, 40 cents.

The OBJECT of the author has been twofold. First and chiefly, to make a book adapted for use in the college class-room; and, secondly, to make one valuable as a permanent storehouse and directory of information for the student's use after he has finished his prescribed course.

The METHOD of treatment corresponds with the object of the book. Truth, accuracy, and order have been aimed at first, with clearness and freedom from ambiguity.

In AMOUNT, the work has been adjusted as closely as possible to the prevailing courses of study in our colleges. The fine print may be omitted from the regular lessons and used as collateral reading. It is important to anything like a complete view of the subject, but not essential to a course. Some entire chapters can be omitted, if necessary.

NEW TOPICS, as indicated above, have received a full share of attention, and while the book makes no claims to novelty, the name of the author is a guarantee of much originality both of matter and manner.

The book will be found especially well adapted for high school and academy teachers who desire a work for reference in supplementing their brief courses. The illustrations are mostly new, and prepared expressly for this work. The tables in the appendix are from the latest and most trustworthy sources. A very full and carefully prepared index will be found at the end.

The eminence of Professor Young as an original investigator in astronomy, a lecturer and writer on the subject, and an instructor of college classes, and his scrupulous care in preparing this volume, led the publishers to present the work with the highest confidence; and this confidence has been fully justified by the event. More than one hundred colleges adopted the work within a year from its publication.

_Young's Elements of Astronomy._

A Text-Book for use in High Schools and Academies. With a Uranography. By CHARLES A. YOUNG, Ph.D., LL.D., Professor of Astronomy in the College of New Jersey (Princeton), and author of _A General Astronomy_, _The Sun_, etc. 12mo. Half leather. x + 472 pages, and four star maps. Mailing Price, $1.55; for Introduction, $1.40; allowance for old book in exchange, 30 cents.

_Uranography._

From Young's Elements of Astronomy. 12mo. Flexible covers. 42 pages, besides four star maps. By mail, 35 cents; for Introduction, 30 cents.

This volume is a new work, and not a mere abridgment of the author's _General Astronomy_. Much of the material of the larger book has naturally been incorporated in this, and many of its illustrations are used; but everything has been worked over, with reference to the high school course.

Special attention has been paid to making all statements correct and accurate _as far as they go_. Many of them are necessarily incomplete, on account of the elementary character of the work; but it is hoped that this incompleteness has never been allowed to become untruth, and that the pupil will not afterwards have to unlearn anything the book has taught him.

In the text no mathematics higher than elementary algebra and geometry is introduced; in the foot-notes and in the Appendix an occasional trigonometric formula appears, for the benefit of the very considerable number of high school students who understand such expressions. This fact should be particularly noted, for it is a special aim of the book to teach astronomy scientifically without requiring more knowledge and skill in mathematics than can be expected of high school pupils.

Many things of real, but secondary, importance have been treated of in fine print; and others which, while they certainly ought to be found within the covers of a high school text-book of astronomy, are not essential to the course, are relegated to the Appendix.

A brief URANOGRAPHY is also presented, covering the constellations visible in the United States, with maps on a scale sufficient for the easy identification of all the principal stars. It includes also a list of such telescopic objects in each constellation as are easily found and lie within the power of a small telescope.

_Plant Organization._

By R. HALSTED WARD, M.D., F.R.M.S., Professor of Botany in the Rensselaer Polytechnic Institute, Troy, N.Y. Quarto. 176 pages. Illustrated. Flexible boards. Mailing Price, 85 cents; for Introd., 75 cents.

It consists of a synoptical review of the general structure and morphology of plants, clearly drawn out according to biological principles, fully illustrated, and accompanied by a set of blanks for written exercises by pupils. The plan is designed to encourage close observation, exact knowledge, and precise statement.

_A Primer of Botany._

By Mrs. A. A. KNIGHT, of Robinson Seminary, Exeter, N.H. 12mo. Boards. Illus. vii + 115 pp. Mailing Price, 35 cents; for Introd., 30 cents.

This Primer is designed to bring physiological botany to the level of primary and intermediate grades.

_Outlines of Lessons in Botany._

For the use of teachers, or mothers studying with their children. By Miss JANE H. NEWELL. Part I.: From Seed to Leaf. Sq. 16mo. Illus. 150 pp. Cloth. Mailing Price, 55 cents; for Introd., 50 cents.

This book aims to give an outline of work for the pupils themselves. It follows the plan of Gray's _First Lessons_ and _How Plants Grow_, and is intended to be used with either of these books.

_A Reader in Botany._

Selected and adapted from well-known Authors. By Miss JANE H. NEWELL. Part I.: From Seed to Leaf. 12mo. Cloth. vi + 209 pp. Mailing Price, 70 cents; for Introd., 60 cents.

This book follows the plan of the editor's _Outlines of Lessons in Botany_ and Gray's _Lessons_, and treats of Seed-Food, Movements of Seedlings, Trees in Winter, Climbing Plants, Insectivorous Plants, Protection of Leaves from the Attacks of Animals, etc.

_Little Flower-People._

By GERTRUDE ELISABETH HALE. Sq. 12mo. Illus. Cloth. xiii + 85 pp. Mailing Price, 50 cents; for Introd., 40 cents.

The aim of this book is to tell some of the most important elementary facts of plant-life in such a way as to appeal to the child's imagination and curiosity, and to awaken an observant interest in the facts themselves.