CHAPTER XVIII

ADAPTATIONS

Most of the discussions which have been presented in the preceding chapters have dealt with the types of compounds, the kinds of reactions, and the mechanism for the control of these, which are exhibited by plants under their normal conditions for development. The results of the evolutionary process have produced in the different species of plants certain fixed habits of growth and metabolism. So definitely fixed are these that in each particular species of plants each individual differs from other individuals, which are of the same age and have had the same nutritional advantages and environmental opportunities for growth, by scarcely perceptible variations, if at all. Indeed, this fixed habit of development makes possible the classification of plants into genera, species, etc. While _different species_ of plants, given the same conditions of nutrition and environment, produce organs of the widest conceivable variety in form, color, and function; within the _same species_, the form and size of leaves, the position and branching of the stem, the color, size, and shape of the flower, the coloration and markings of the fruit, etc., are relatively constant and subject to only very slight modifications.

It is unnecessary to say that the mechanism, or the impulses, which govern the morphological characters of the tissues which any given species of plants will elaborate out of the crude food material which it receives from the soil and atmosphere, are wholly unknown to science. It is the commonly accepted assumption that the fixed habit of growth of the species is transmitted from generation to generation through the chromosomes of the germ cells. But the nature of the elements, or substances, which may be present in the chromosomes, which influence the character of the organs which will develop months later, after the plant which grows from the germ cell has gone through its various stages of vegetative growth, is still altogether unknown. There can be no question, however, that some influence produces a fixity of habit of growth and development which is almost inevitable in its operation.

But while this unvarying habit of growth is one of the fixed laws of plant life, there are occasional deviations from it. A plant which, under normal conditions of growth, develops in a certain fixed way, when exposed to unusual environmental conditions, may, and often does, alter its habit of growth in what may metaphorically be said to be an attempt to adjust itself to the new conditions. Numerous examples of this phenomenon might be cited. Certain algæ, which grow normally in water at a temperature of 20° to 30° and which are killed if the temperature rises above 45°, have been grown for successive generations in water the temperature of which has been gradually raised, until they produce apparently normal growth in water the temperature of which is as high as 78°; also, certain types of algæ normally grow in the water of hot springs at temperatures of 85° to 90°, and others in arctic sea-water the temperature of which sometimes falls to -1.8° and never rises above 0° C. This phenomenon of the adjustment of a species of plants to new conditions, which in the case of farm crops is sometimes called "acclimatization," is of common occurrence and is often utilized to economic advantage in the introduction of new strains of crops into new agricultural districts. Again, the normal development of plants may be altered as the result of injury or mutilation. Thus, if the ear is removed from the stalk of Indian corn, at any time after flowering, there always results an abnormal storage of sucrose in the stalk, instead of the normal storage of starch in the kernels. Similarly, midsummer pruning of fruit trees generally results in the production of abnormally large number of fruit buds on the remaining limbs. Many other familiar examples of alteration of normal development in response to, or as the result of, abnormal conditions of growth might be cited.

TYPES OF ADAPTATIONS

To designate these different alterations of normal growth, several different terms have been used. Among these, "adaptation," "accommodation," and "adjustment" have been commonly used by different biologists. Sometimes these are used interchangeably, and sometimes different terms are used to designate different types of response to altered conditions of growth. Inasmuch as there seems to be no generally accepted usage of these different terms, only one of them, namely, the word "adaptation" will be used here; and different manifestations of this phenomenon will be distinguished by using appropriate adjectives, as "physiological adaptations," "chromatic adaptations," "morphological adaptations," etc.

Two markedly different types of responses to altered conditions, or of adjustment to environment, may be recognized. In the first of these, for which we will use the term "physiological adaptation," the species of plant simply acquires the ability to exist and grow normally under conditions which formerly inhibited its growth. Thus, we may speak of the phenomena mentioned above as "acclimatization" as the _physiological adaptation_ of the crop to the new conditions of growth. In general, physiological adaptations include such variations in the characters or habits of growth of plants as results in differences in resistance to heat or to cold, relations to water, aggressiveness in competition with other plants, etc. In such cases, no modification of the morphological characters of the plant can be observed, the changes which take place in the structure of the plant (if, indeed, there be any such changes) must be only minor adjustments of the protoplasm to meet the new environmental needs.

In the second type of adaptations, for which we will use the term "morphological adaptations," the structure, or color, or some other morphological character of the plant is actually changed in some easily recognizable way, in order that the plant may be better adjusted to its environment. As examples of _morphological adaptations_, there may be cited the change in color of sea-weeds with increasing depth in the sea, and other examples of chromatic adaptation which are discussed below; the development of fewer, or a larger number, of buds on the above-ground stems of plants, in response to decreases, or increases, in the available supply of food; the alteration in the size and shape of the leaves of many plants when they are grown in shade; the dwarfing of plants at high altitudes, or under conditions of severe drought; the development of underground storage organs for certain species of shrubs and trees which grow in regions that are subject to periodical burning-over, in such a way as to destroy the above-ground storage stems, etc.

Hence, the two terms, as we will use them here, may be defined as follows: _morphological adaptation_ is a change in the structural character of the species in order that it may be better fitted to meet the needs of the new conditions of growth; while _physiological adaptation_ is an acquired power to survive and develop under abnormal conditions, which is not accompanied by any visible change in the characteristic structure of the species.

Both of these types of adjustment may be either hereditary (or evolutionary), or spontaneous in their origin and development. Changes which are evolutionary are fixed by heredity and become definite habits of growth in the species. Their origin may be explained in either one of two ways; namely, the so-called "increase by use," and "the survival of the fittest." The hypothesis of "increase by use," as an explanation of adaptations, is based upon the well-known observation that, in animals, muscles and other organs increase in volume as they are extensively used; and the assumption of the application of this principle to the phenomenon of adaptation supposes that the modification of any given structure or composition is the result of the hereditary accumulations of increased size resulting from use, or of atrophy from disuse. The "survival of the fittest" theory supposes that individuals of a species differ from each other by spontaneous variations, and that in the competitive struggle for existence those forms which are best adapted to the environmental conditions survive while the others perish. The contrast between these two views is that the first holds that adaptation proceeds by development, and the second that it proceeds by variation and elimination; the first presupposes the existence in the organism of a mechanism for response to changing conditions, and the second assumes that there are chance variations followed by the death through competition of the forms which are not able to meet the needs of the environment.

Confusion arises whenever an attempt is made to apply either of these theories to all kinds of adaptations. The idea of increase by use can be applied with some satisfaction to certain morphological adaptations in animal structure; and to such phenomena as the increase in strength of the branches of fruit trees, either with or without corresponding increase in size, as the load of fruit increases. But it certainly cannot apply to color change in surface pigmentation of either animals or plants, which is one of the most common forms of adaptation. Furthermore, it is difficult to conceive the general application of this idea to alterations of habits of growth of plants, since a plant cannot have any such thing as a voluntary control over the amount of "use" which it makes of its different organs in response to changes of environment. The common form of statement that a plant develops an organ, or a process to meet a certain need, or modifies its habits of growth to meet a change of environment are, of course, purely metaphorical, and can only be taken to mean that such processes are mechanical responses to changes in external conditions.

The nature of the mechanism by which these responses are accomplished is, as yet, wholly unknown. There is accumulating a large mass of experimental evidence which goes to show that, while both temperature and light are very important factors in determining the type of changes which will take place in a living organism, the so-called "photochemical action of light" is by far the most potent of all the climatic factors which influence the course of development of a plant. But we have, as yet, no inkling of how the protoplasm of the plant adjusts or controls its responses to variations in any of these external factors.

With these general considerations in mind, we may now proceed to the consideration of certain particular types of adaptations.

CHROMATIC ADAPTATIONS

Adaptations have been observed in both the energy-absorbing pigments of the general tissues and in the ornamental epidermis pigments of plants. The former are by far the most important from the physiological point of view; while the latter may have interesting biological significance.

Under nearly all conditions of growth of land plants, the supply of the chlorophylls and their associated pigments provides for the absorption of solar energy far in excess of the amount necessary for the photosynthetic assimilation of all the carbon dioxide which is available to the plant. It has been shown that an active green leaf, on an August day, can absorb eight times as much radiant energy as would be required to assimilate all the carbon dioxide present in the air over its surface. No land plant, under normal conditions, develops supplementary pigments in order to utilize other than the parts of the spectrum which are absorbed by chlorophyll and its associated pigments.

But deep-sea plants show quite a different phenomenon of pigment development. Water is a blue liquid. At depths of 40 feet or more, the light which penetrates is devoid of red rays, feeble in yellow, and is characteristically green or blue in color. Now, the red rays of the spectrum are the ones which are most efficient for photosynthesis. Sea weeds which grow at these depths are brilliantly red in color, at intermediate depths they are brown, and at the surface they are green, in the same latitudes. While it is possible that the temperature of the water at these different depths may have something to do with the chemical synthesis of the pigments, it appears plain that this color change at increasing depths is a definite adaptation to provide for the absorption of the solar energy which is available at these depths. It has been shown that these pigments of deep-sea plants are additional to, and not substitutes for, the chlorophylls, etc. The latter pigments are present in normal amounts, but are supplemented by those which absorb the green and blue portion of the spectrum. Hence, this type of adaptation might be conceived to be a "survival of the fittest," resulting in the "natural selection" of individuals of the highest total pigmentation. But, on the other hand, there is experimental evidence to show that plants possess some means of varying their pigmentation in response to the character of the light which comes to them. For, it has been found that a complete change in color of certain highly colored plants can be produced in a single generation, by growing the plants in boxes or chambers whose walls are composed entirely of differently colored glass, so that the plants within receive light of only a particular part of the spectrum. In such cases, the plant, starting with an initial "natural" color, changes through a succession of colors until it finally reaches equilibrium at one which provides for the proper absorption of the right kind of light from the new supply which is available to it. Hence, it seems proper to conclude that chromatic adaptation is not a process of "natural selection," but a definite result of an actual mechanism for adaptation to changed environmental conditions of supply of radiant energy.

STRUCTURAL ADAPTATIONS

Changes in structure to meet special conditions of growth may be of several different types.

One of these, which is often cited as an example of adaptation (in this case, the term is used with a significance quite different than that in which it is being used here) is that of the development of unusual and often fantastic shapes of flowers, which are so related to the anatomy of certain species of insects that visit these flowers in search of nectar, that provision for the cross-fertilization of the plants is insured, in that the pollen from the anthers of one flower becomes lodged on the body of the insect as it is withdrawing from the flower in such a way that it comes in contact with the pistil of a second flower as the insect enters it. Such flowers often have such peculiar shapes and lengths of nectar tubes, etc., that only a single species of insect, whose anatomical shape is "adapted" to that particular blossom shape can enter the flower in its search for nectar. It is clear that this form of "morphological adaptation" is a highly specialized one, which can only be the result of a long process of evolutionary development. It is obvious that the plant cannot possibly possess a mechanism, or ability, to alter its flower form in order to make it conform to the shape and length of the proboscis, or other body parts, of a particular species of insect. Either the insect or the plant, or both, must go through a process of evolutionary development in order to arrive at this form of mutual "adaptation."

A form of true morphological adaptation (in the sense in which we have been using the term) is exhibited by many species of plants, which are provided with many more buds, or growing points, than ever actually begin to grow. For example, the single plumule which develops from a germinating wheat embryo has at its upper end a hundred or more tiny growing points. At the proper stage of its growth, several of these tiny buds begin to grow into individual separate stems, and the new wheat plant thus produces several stems from one seed and root system, a process known as the "stooling." The number of stems in a single "stool" depends upon the number of the potential growing points which are stimulated into growth. It varies from only two or three up to as many as thirty or forty, and is apparently controlled by the favorable or unfavorable conditions of climate or nutrition at the time when the "stooling" takes place. The plant is thus provided with a mechanism for adapting its possibilities of growth to the supply of growth-promoting material which is available to it.

Many other plants produce far more buds than ever develop into growing tissues, and buds which, under normal conditions, remain dormant, under altered conditions start into growth and so provide for an "adaptation" of the total mass of the growing plant to correspond with the altered conditions of growth. The actual means by which certain buds are stimulated into growth while others remain dormant, or are inhibited from growing, are as yet unknown. Two theories have been advanced. One is that the growing buds absorb all available nutrition and the others remain dormant by reason of lack of growth-promoting material. The other is that the vegetating (growing) tissue elaborates and sends to other parts of the organism one or more substances, which actually inhibit growth of the other parts, as dormant buds, etc. The experimental evidence which has been presented thus far is inconclusive, but seems to favor the distribution of nutritional material as the governing factor, although there is some evidence which seems to indicate that a supposed growth-inhibiting substance is actually translocated from rapidly-vegetating tissues to other parts of the plant. There is, however, no explanation of how the buds, or other tissues, which do grow get their initial stimulus, while the dormant buds do not. After growth has once started, the changes in osmotic pressure due to the accumulation and translocation of synthetized materials can account for the movement of new nutritional material for the synthetic processes into the growing organ; but this would not account for the selective stimulation of only a part of the buds, or possible growing points, of a plant, or for an adaptational development of others under altered conditions of growth.

The form of morphological adaptation which has been discovered in the course of the study of the native vegetation of the campos of Brazil (which have a very dry season and have been regularly burned over by the natives for many generations) in which the papilionaceous shrubs have developed underground trunks, or stems, and seem actually to profit in luxuriance of growth when the rainy season comes on by reason of this morphological adaptation to the unusual environmental conditions, is wholly inexplicable by any present knowledge of the science of plant growth.

PHYSIOLOGICAL ADAPTATIONS

The type of adjustment to environmental conditions which does not result in any recognizable alteration in the structure of the plant, but simply permits it to grow under new conditions, manifests itself in many ways. These adjustments are usually associated with differences in temperature during the growing season, and for this reason, most such examples of adaptation have been studied in connection with possible temperature reactions upon the growing organism.

However, recent investigations seem to point strongly to the conclusion that the amount of _light_ rather than the _temperature_ of the new surroundings is the most important influence in determining the physiological processes known as the "acclimatization" of plants. For example, a very elaborate series of investigations has shown that the flowering stage in the development of plants is determined by the length of the daylight period per day, irrespective of the actual amount of vegetative growth which the plant has made. Thus, tobacco plants, which during a period of long days grow to the height of 8 or 10 feet before blossoming, if grown at the same temperature in periods of short days (or if kept in the dark during a portion of the longer days) will blossom when less than 3 feet in height and when the total mass of vegetative material which has been produced is less than one-third of that of the "gigantic" plants of the same variety grown with longer periods of illumination per day. This same principle has been found to hold good for many widely different types of plants. In some species, however, flowering is favored by long days, and vegetative growth by short daylight illumination. But in all species which have been studied, there seems to be a direct relation between the length of day, or the total illumination per day, and the normal or abnormal functioning of the plant. It is apparent that at least the physiological function of sexual reproduction (flowering and seed-production) is determined by the length of daylight illumination. The duration of daylight per day which is necessary to induce the blossoming of the plants varies for different species, but it is constant for individuals of the same species. This adaptation of stage of growth to duration of daily illumination must, therefore, be an evolutionary character of the species.

Hence, it appears that in many cases physiological adaptation may be a direct response of the life-processes of the plant to the daily length of photochemical stimulation which it receives from solar light. But there is, as yet, no explanation of how this (or any other) influence actually changes the vital processes of the plant protoplasm so as to bring about either a morphological adaptation of structure or a physiological adaptation of functions to altered conditions of growth.

CONCLUDING STATEMENTS

Enough has been said to show how very inconclusive and unsatisfactory is our knowledge of the phenomena known as "adaptation." Even the nomenclature used by different scientists to describe its various manifestations is confused and misleading. For example, certain crops are said to be "adapted" (i.e., suited) to certain types of soils, and _vice versa_; crops are said to be "adapted" to given agricultural districts, etc.

In this chapter, an attempt has been made to arrange in some semblance of order some of the known manifestations of alteration of fixed habits of growth of plants in response to changes of environment, and to point out some of the suggestions of possible explanations of these phenomena which have been presented by different investigators.

This presentation cannot be considered as anything other than an introduction to a field of study which is as yet almost entirely unexplored, and, like all other unexplored territory, is full of mysteries. If the study of this chapter serves to stimulate interest in these mysteries and wonders of plant life, its purpose will have been accomplished.

INDEX

Bold-face figures indicate main references

Accelerators, 196. Accessory substances, 19. Achroo-dextrin, 61. Acid, acetic, 125, 126, =128=, 132, 133, 166. arabic, 68. arachidic, 133. aspartic, 168, 177. brassic, 133. butyric, 126, 133. capric, 133. caprylic, 133. carnaubic, 140. cerotic, 133, 140. citric, 125, 127. convolvulinic, 81. crotonic, 133. diamino-oxysebacic, 169. diamino-trioxydodecanic, 169. digallic, 96. ellagic, =96=. euxanthic, 84. formic, 25, =126=, 128, 132. galactonic, 42. gallic, =96=. geddic, 69. gluconic, 42. glucuronic, 42, 43. glutamic, 168, =177=. glycero-phosphoric, 142. hydrocyanic, 77. jalapinic, 81. lauric, 133. lignoceric, 133. linoleic, 133. linolenic, 133. malic, 124, =127=. malonic, 124. mannonic, 42. melissic, 133. meta-pectic, 68, =70=. mucic, 68. myristic, 133. nitric, 125. nucleic, =162=. oleic, 133. oxalic, 68, 124, 125, =126=, 128. palmitic, 133, 140. parapectic, 70. pectic, =31=, 70. phosphoric, 141, 142, =162=. propionic, 126, 166. pyrocatechuic, 96. quercitannic, =98=. racemic, 54. ricinoleic, 133. ruberythric, =83=. saccharic, 42, 68. salicylic, 81. sarco-lactic, =128=. stearic, 131, =133=. succinic, =127=, 128. sulfuric, 125. sylvinic, 149. talonic, 42. tannic, 97, =127=. tartaric, =127=. uric, =160=. xanthoproteic, 173. Acid amides, 151. Acidity of protoplasm, =234=. Acid glucosides, 81. Acid potassium oxalate, 125. Acid potassium sulfate, 88. Acid salts, =124=. Acids as toxins, =246=. Acid sodium sulfate, 125. Acrolein, 135. Acrose, 28. Activators, 196. Adamkiewicz's reaction, 173. Adaptations, =249=. Adenase, 190. Adenine, =160=, 162. Adipo-celluloses, =74=. Adsorption, =214=. Æsculetin, 81, 82. Æsculin, =81=, 82. Ætiophyllin, 106, 107, 109. Ætioporphyrin, 108, 109, 110. Alanine, 168, 177. Albumins, 175, 176. Albuminoids, 175, 176. Alcogel, 205. Alcohol, ethyl, 40, 125. benzyl, 80. carnaubyl, 135. ceryl, 135, 140. cetyl, 129, 135. coniferyl, 80. melissyl, 135. myricyl, 129, 140. phytyl, 104, =105=. polyhydric, 31. Alcohol glucosides, 80. Alcosol, 205. Aldehyde, benzoic, 148. cinnamic, 148. formic (_see_ formaldehyde). glyceric, 35. Aldehyde glucosides, 80. Aldehydrol, 46. Aldonic acids, 42, 44. Aldose, 32. Alizarin glucosides, 78. Alkalinity of protoplasm, 234. Alkalies as toxins, =247=. "Alkali salts," 10, =247=. "Alkali soils," 10, =14=. Alkaloidal reagents, 154, 172. Alkaloids, 18, 20, 151, =153=, 248. Allose, 36, 37. Allyl isosulfocyanide, 88, 89, 148. Allyl sulfide, 148. [alpha]-glucose, 46. [alpha]-glucosides, 55. [alpha]-methyl glucoside, =47=. Altrose, 36, 37. Aluminium, =4=. Amandin, 170, 176. Amines, =151=. Amino-acids, 6, 151, =166=, 179, 248. Ammonia, 152. Ammonium hydroxide, 142, 152. Ammonium salts, 6. Amorphous chlorophyll, 104, 105 Amphoteric electrolytes, 172. Amygdalase, 87. Amygdalin, 81, =86=. Amyl acetate, 148. Amylase, 186, 189, =191=. Amylo-cellulose, 60. Amylo-dextrin, 61. Amylo-pectin, 60. Amylose, 60. Anergic food, =2=, 17. Animal nucleic acids, =162=. Antagonism, 14. Anthocyans, 83, 102, =115=, 121. Anthocyanidins, 116. Anthocyanin, 102. Anthoxanthins, =117=. Anthraquinone, 83. Antienzymes, 120, =197=, 198. Antioxidase, 120. Antiscorbutic C, 243. Apigenin, 84, 118. Apiin, =84=. Apiose, 84. Araban, =69=. Arabinose, 35, 44, 68, 69, 88. Arabinosides, 56. Arbutin, 77, =79=. Arginine, 169, 171, 177. Arsenic, 13. Asymmetric carbon atom, 33. Atropine, 155, =156=. Autotrophic plants, 16, 18. Auximones, 239, 240, =244=. Available plant food, =4=. Avenalin, 176.

Baptigenin, 79. Baptisin, =79=. Beeswax, 133. Beet sugar (_see_ sucrose). Berberine, 155. Betaine, =152=. [beta]-glucase, 55. [beta]-glucose, 46. [beta]-glucosides, 55. [beta]-methyl glucoside, 47. Biogens, 223. Biological significance, =19=. Biuret reaction, 173. Borneol, 148. Boron, 13. Bromelin, 189. Brucine, 155, =157=. Buffers, 236. Butter fat, 133. Butyric acid ferment, 190.

Cadaverine, 152. Caffeine, =160=. Calcifuges, 9. Calciphiles, 9. Calcium, 3, 5, =9=, 10, 14, 68. Calcium oxalate, 126. Campferitrin, 118. Campferol, 118. Camphene, 147. Camphor, 148. Cane sugar (_see_ sucrose). Caoutchouc, =147=. Capillary segregation, 235. Carbohydrases, 189. Carbohydrates, 18, 20, =21=, =30=, 163, 234. Carbon dioxide, 2, 3, 18, =21=, 22, 23, 24, 40, 222. Carbonic acid, 227. Carbon monoxide, 24. Carboxyl, 124. Carboxylases, 186, 190. Carnauba wax, 133, 140. Carotin, =112=, 113, 121. Carotinoids, 102, =111=. Carvacrol, =148=. Casein, 165. Castanin, 176. Castor oil, 130. Catalases, 190, 193. Catalysis, 182. Catalysts, 17, 25, 183. Catechol tannins, 97. Catechin, =97=. Catechu tannins, =97=. Cellobiose, 52. Cell structure, 221. Cellulase, =71=, 186, 189. Celluloid, 73. Cellulose, 20, 45, 63, 67, =72=. Cell-wall, 9, 12, 222. Cerebrosides, 141, =144=. Chemical resistance, 216. Cherry gum, 68. Chinovose, 35. Chlorine, =12=. Chlorophyll, 10, 11, 21, 27, =102=, 105, 110, 111, 113, 122, 254. Chlorophyll _a_, 103, 106, 107, =111=. Chlorophyll _b_, 103, 106, 108, =111=. Chlorophyllase, 104. Chlorophyllin _a_, 106, 107. Chlorophyllin _b_, 106, 107. Cholesterol, 129, =136=. Choline, 89, 103, 141, 142, =152=. Chromatic adaptations, 251, =253=. Chromogens, 92, 119. Chromo-proteins, 175. Chrysin, 117. Cinchonine, 155, =157=. Coagulated proteins, 175. Coagulation enzymes, 190. Cocaine, 155, =157=. Cocoanut oil, 133. Codeine, 155, =158=. Coenzymes, =197=. "Cold-drawn oils," 137. Collodion, 73. Colloidal phenomena, 17, =202=. Colloidal solutions, 204. Colloids, 202. Colophene, 147. Colophony, 149. Compound celluloses, 71, =73=. Conglutin, 176. Coniferin, =80=. Coniine, 155, =156=. Conjugated proteins, 165, 174, =175=. Continuous phase, 203. Convolvulin, =81=. Copper, 13, 247. Cork tissue, 99, 101. Corn oil, 130. Corylin, 176. Cottonseed oil, 130. Critical elements, 4. "Crude fat," 141. Crystalline chlorophyll, 104, 105. Crystalloids, 202. Cumarin, 81, 148. Curarine, 157. Cuto-celluloses, =74=. Cyanidin, 85, 116. Cyanin, =85=. Cyanophore glucosides, 86. Cyanophyllin, 107, 108. Cyanoporphyrin, 108. Cymarigenin, 90. Cymarin, =90=. Cymarose, 90. Cystine, 168, 171. Cytase, 72, 189. Cytosine, 161, 162.

Daphnetin, 81, 82. Daphnin, 81. Deaminases, 186, 190. Delphinidin, 85, 116. Delphinin, =85=. Derived proteins, 173, =175=, 177. Dextrin, 59, =61=. Dextrinase, 189. _d_-galactose, 33. _d_-glucose, 33. Dextrosans, 59. Dextrose (_see_ glucose). Dhurrin, =87=. Diastase (_see_ amylase). Diastase of secretion, =191=. Digitaligenin, 89. Digitalin, =89=. Digitogenin, 89. Digitonin, =89=, 90. Digito-saponin, 90. Digitoxigenin, 89. Digitoxin, =89=. Digitoxose, 89. Diglycerides, 131. Diose, 30. Dioxyacetone, 35. Dipeptides, 167. Disaccharides, 31, =48=. Dispersed phase, 203. Dispersion medium, 203. Dispersion phenomena, 203. Drying oils, 132. Dulcitol series, 36.

Edestin, 170, 176. Egg-albumin, 165. Electrical phenomena of protoplasm, =233=. Electrolytes, 213, 227. Emulsoids, 206, 214. Emulsions, 206. Emulsin, 55, 77, 87, 184, 189. Enol, =44=, 56. Enzymes, 17, 18, 19, 20, 23, 26, 120, 121, =181=, 183, 194, 199, 224. Erepsin, 189. Erythro-dextrin, 61. Erythrophyllin, 107. Erythrose, 35. Essential elements, 4. Essential oils, 18, 146, =147=, 224. Esterases, 186, 189. Esters, 124, 125, 129. "Ether extract," 141. Etherial salts (_see_ esters). Ethersol, 205. Ethyl acetate, 125. Ethyl nitrate, 125. Excelsin, 176. Extracellular enzymes, 184.

Fats, 18, 20, =129=, 224, 227. Fat-soluble A, =243=. Fatty acids, 132, 142. Fehling's solution, 39, =47=. Fermentability, =40=. Ferments (_see_ enzymes). Ferric salts, 11. Ferrous salts, 11. Fisetin, 118. Flavone, 82, 83, 102. Flavonol, 84. Food, =1=. Formaldehyde, =22=, 23, 25, 26, 27, 247. Frame-work material, 20, 67. Fraxetin, 82. Fraxin, =82=. Fructose, 23, 28, 32, 36, 38, 41, 44, 45, =47=, 57, 162. Fructosides, 41, 42. Fruit sugar (_see_ fructose). Fucose, 35. Fucoxanthin, 102, 112, 114.

Galactans, 47, 59, =63=, 72. Galactoheptose, 36. Galactooctose, 36. Galactose, 32, 36, 38, 45, =47=, 57, 72, 77. Galactosides, 41, 42. Gaultherin, 81. Gel, 172, 205, 208. Gelation, 210. Gel-formation, =208=, 211. Gentianose, 52, =53=. Gentiobiose, 49, =52=, 53. Gentisin, 119. Gitaligenin, 89. Gitalin, =89=. Gitogenin, 89. Gitonin, =89=. Glaucophyllin, 107. Gliadin, 165, 170, 176. Globulins, 170, 175, 176. Glucase, 186. Glucodecose, 44. Glucoheptose, 36, 44. Glucononose, 36. Glucooctose, 36. Glucoproteins, 175. Glucose, 23, 28, 32, 36, =37=, 40, 41, 42, 43, 44, 45, 46, 57, 77. Glucosidases, 189. Glucosides, 18, 20, 41, 48, 55, =76=, 91, 93. Glue, 210. Glutelins, 175, 176. Glutenin, 176. Glycerine (_see_ glycerol). Glycerol, 129, 131, =134=, 142. Glycine, 166, 168, 177. Glycinin, 176. Glycogen, 59, =61=. Glycyphyllin, =79=. Graminin, 59, =62=. Granulose, 60. Grape sugar (_see_ glucose). Guanase, 190. Guanine, =160=, 162. Gulose, 36, 37. Gum arabic, =68=. Gums, 62, 67, =68=. Gum tragacanth, =69=. Gun-cotton, 73.

Hæmatin, 110. Hæmatinic acid imide, 109. Hæmatoporphyrin, 110. Hæmoglobin, 110. Hæmopyrrole, 109. Helicin, 81. Hemi-celluloses, 63, =71=. Hemi-terpenes, 147. Heptoses, 30. Hesperidin, =79=. Hesperitin, 79, 80. Heterotrophic plants, 16. Hexosans, 59, 67. Hexoses, 22, 28, 30. Histidine, 169, =177=. Histones, 175, 176. Honey sugar (_see_ fructose). Hordein, 153, 170, 176. Hormones, 92, 239, =240=. "Hot-drawn oils," 137. Humins, 67. Hydrastine, 155. Hydrazones, 40, 49. Hydrocellulose, 73. Hydrogen peroxide, 26, 27, 190. Hydrogel, 205. Hydrolases, 186, 189. Hydroquinone, 77, 79. Hydrosol, 205. Hydroxy-phenyl ethyl amine, 153. Hygrine, 155, 156. Hyoscine, 155. Hyoscyamine, =156=. Hypoxanthine, =160=.

Idain, =85=. Idose, 36, 37. Illuminating gas as a toxin, 247. Imbibition, 209. Impermeable membranes, 228. Indian yellow, =84=. Indican, 78, =85=. Indigo, 78, 84. Indigotin, 85. Indole, 158. Indoxyl, 85. Inhibitors, 196. Intracellular enzymes, 184. Inulin, 59. Inulinase, 62, 189. Invertase, 50, 189, =191=. Invert sugar, 47, 50. Iodine number, 138. Ionization phenomena, 226. Iridin, =79=. Irigenin, 79, 80. Iron, 3, 5, 11, 110. Isochlorophyllin _a_, 106, 107, 108. Isochlorophyllin _b_, 106, 107, 108. Isohæmopyrrole, 109. Isoleucine, 168. Isomaltose, 51. Isomerism, 32. Isoprene, 147. Isoquercitrin, 84. Isoquinoline, 155.

Jalapin, =81=. Japan wax, 129. Juglansin, 176.

Ketose, 32.

Lactam, 104. Lactase, =56=. Lactic acid ferment, 190. Lactone, 104. Lactose, 45, 49, 52. Laudanosine, 158. Laudanum, 158. Lecithin, 7, =141=, 142, 143. Lecithoproteins, 175. Legumelin, 176. Legumin, 170, 176. Leucine, 115, 168, =177=. Leucomaines, 152. Leucosin, 176. _l_-galactose, 33. _l_-glucose, 33. Levulosans, 59, =62=. Levulose (_see_ fructose). Lichenin, =62=. Light, 21, 253, 257. Lignocelluloses, =74=. Lignose, 31. Limettin, =82=. Limonene, 147. Linalyl acetate, 148. Linseed oil, 133. Lipases, 186, 189. Lipins (_see_ lipoids). Lipoids, 129, =140=. Lipoproteins, 175. Lupinine, 155. Lycopersicin, 102, 122, =114=. Lysine, 169, 171, 177. Lyxose, 35.

Magnesium, 3, 5, 9, =10=, 11, 13, 14, 68. Maltase, 55, 184, 189. Maltose, 45, 49, =51=, 52. Malvidin, 85. Malvin, =85=. Mandelo-nitrile, 78, 88. Mandelo-nitrile glucoside, 77, 87. Manganese, =4=, 13. "Manna," 47. Mannans, 59, 62, =63=, 72. Mannite, 47. Mannitol, 47. Mannitol series, 36. Mannoheptose, 36, 44. Mannononose, 36. Mannooctose, 36. Mannosans (_see_ mannans). Mannose, 32, 36, 37, 41, 44, 45, =47=, 57, 72. Mannosides, 42. Maple sugar (_see_ sucrose). Maysin, 176. Melibiose, 49, =52=. Melizitose, =52=. Menthol, 148. "Mercerizing" cotton, =73=. Mercury, 247. Merosinigrin, 88. Metallic salts, 13, 224, 227, 237, 247. "Metal proteids," 14. Meta-pectin, 70. Metaproteins, 175. Methylethylmalein imide, 108. Methyl glucosides, 42. Methyl pentoses, 35. Methyl salicylate, 81. Middle lamella, 67, 70. Millon's reaction, 173. Molisch's reaction, 174. Monoglycerides, 131. Monohydric alcohols, 135. Monosaccharides, 31, =35=, 45. Morin, 119. Morphine, 155, =158=. Morphological adaptations, 251, 252, =255=. Mucilages, 67, =70=. Muco-celluloses, 74. Muscarine, =152=. Mustard oils, 88, 148. Mustard oil glucosides, 88. Mutarotation, 46, 49. Myrosin, 77, 88, 149, 189. Myrtillidin, 85. Myrtillin, =85=.

Narceine, 158. Narcotine, 158. "Natural selection," 254. Neurine, 152. Nicotine, 155, =156=. Nitrates, 6. Nitrile reaction, =43=. Nitriles, 43, 44. Nitrogen, 3, 5, 6, 151, =164=. Non-drying oils, 132. Non-essential elements, 4. Non-reducing sugars, 39, 49. Nonoses, 31. Normal celluloses, =72=. Nuclease, 189. Nucleoproteins, 162, 175. Nutrients, 1.

Octoses, 31. [OE]nidin, 85, 116. [OE]nin, =85=. Oils, =129=. Oil of bergamot, 148. Oil of bitter almonds, 86, 148. Oil of cassia, 148. Oil of cinnamon, 148. Oil of garlic, 148. Oil of lavender, 148. Oil of mustard, 148. Olive oil, 130. Opium, 158. Organic acids, 18, =124=, 248. Organized ferments, 183. Ornamental pigments, =102=, 123. Ornithine, 169. Oryzenin, 176. Osazones, 40, 41, 49. Osmotic pressure, 213, 228. Osones, 41. Oxidases, 186, 190, 193. Oxime, 44. Oxycellulose, 73. Oxycumarin glucosides, 81. Oxygenated oils, =147=. Oxyhydroquinone, 95. Oxyproline, 169.

Pæonidin, 85. Pæonin, =85=. Palm oil, 133. Papain, 189. Papaverine, 155, =158=. Para-dextran, 62. Para-isodextran, 62. Paralyzers, 196. Para-pectin, =70=. Parasites, 16. Peanut oil, =133=. Pectase, 71. Pectinase, 189. Pectins, 20, 31, 67, =70=. Pecto-celluloses, =74=. Pectose, 31, 70. Pelargonidin, 85, =116=. Pelargonin, =85=. Pentosans, 31, 67, 68, 72. Pentoses, 30, 162. Pepsin, 167. Peptids, =166=, 167, 176. Peptones, 176. Permeable membranes, 228. Peroxidases, 190. Persimmons, 100. Persuelose, 36. Phæophytin, 107, 108. Phaselin, 176. Phaseolin, 176. Phenol, 95. Phenol glucosides, =79=. Phenyl alanine, 168, =177=. Phenyl hydrazine, 40. Phlein, =62=. Phloretin, 79. Phloridzin, =79=. Phloroglucinol, 95. Phosphates, 7. Phosphatides, 141, =143=. Phosphoproteins, 175. Phosphorus, 3, 5, =7=. Photo-chemical action of light, 253, 257. Photolysis, 26. Photosynthesis, 7, 8, 18, 21, 22, =24=, 254. Phycoerythrin, 102, =115=. Phycophæin, 102, =115=. Phyllins, 106, 107. Phyllophyllin, 107. Phyllopyrrole, 109. Physiological adaptations, 252, =257=. Physiological use, =19=. Phytase, 189. Phytochlorin, 108. Phytorhodin, 108. Pigment glucosides, =82=. Pigments, 18, =102=, 224, 254. Pinene, 147. Piperidine, 154. Piperine, =155=. Plant amines, =151=, 152, 163. Plant food, =1=. Plant nucleic acids, =162=. Polybasic acids, 124. Polyhydric alcohols, 31. Polypeptides, 167. Polysaccharides, =59=. Polyterpenes, 147. Poppy wax, 140. Populin, =80=. Porphyrins, 108. Potassium, 3, 5, 8, 10, 13, 14. Primary amines, 152. Proenzymes, 198. Proinulase, 199. Proinvertase, 199. Prolamins, 175, 176. Proline, 169, 177. Prolipase, 199. Prooxidase, 199. Protamines, 175, 176. Proteans, 175. Proteases, 186, 189, =192=. Protective colloids, 209. Proteins, 7, 18, 20, 151, 162, 163, =164=, 224. Proteoses, 175. Protoplasm, 17, 26, 221. Prulaurasin, 87. Prunase, 87. Prunasin, 87. Ptomaines, 152. Purine, =159=. Purine bases, 151, =159=, 162. Purpurin, 83. Putrescine, 152. Pyrimidine, 161. Pyrimidine bases, =161=, 162. Pyrocatechol, 95. Pyrogallol, 95. Pyrogallol tannins, =97=. Pyroxylin, 73. Pyrrophyllin, 107. Pyrridine, 154. Pyrrolidine, 154.

Quaternary amines, =152=. Quercetin, 84, 118. Quercitrin, =84=. Quinine, 155, =157=. Quinoline, 155, 158.

Radiant energy, 19. Raffinose, 45, 52, =53=. Rape-seed oil, 130. Reducing sugars, 39, 49. Reductases, 186, 190. Reserve food, 21. Resenes, 149. Resins, 18, 146, =149=. Resorcinol, 95. Respiration, 18, 121, 235, 236. Rhamnase, =77=, 189. Rhamnetin, 84. Rhamnose, 35, 52, 77, 79. Rhodeose, 35, 81. Rhodophyllin, 107. Ribose, 35. Ricin, 176. Rubiadin, 83. Rubiphyllin, 107.

Saccharide, =31=. Salicin, =80=. Saligenin, 80. Salinigrin, =81=. Salts, 224, =227=, 237. Sambunigrin, 87. Sapogenins, 90. Saponification, 134. Saponification value, 138. Saponins, =90=. Sapotoxins, 90. Saprophytes, 16. "Saturated" acids, 132. Scopolin, =82=. Secalin, =63=. Secondary amines, 152. Secretions, 20. Sedoheptose, =36=. Semipermeable membranes, =228=. Sensitizers, 27. Serine, 168. Silicates, 12. Silicon, 4, =12=. Silver, 247. Simple proteins, 165, 174, =175=. Sinalbin, 89. Sinalbin mustard oil, 89. Sinapin acid sulfate, 89. Sinigrin, =88=. Sinistrin, =62=. Sitosterol, 136. Skimmetin, =81=, 82. Skimmin, =81=. Soaps, 134, 208. Sodium, 4, 9, =12=, 13, 14. Sodium stearate, 133. Sol, 205. "Soluble starch," 60. Sorbitol, 48. Sorbose, 36, 38, 45, =48=. Specific rotatory power, =38=, 39. , of fructose, 39, 47. , of galactose, 49. , of glucose, 39, 47. , of maltose, 51. , of raffinose, 53. , of sucrose, 39. Spermaceti, 129, 133. Stachydrine, 155. Stachyose, 54. Starch, 8, 22, 28, 30, 31, 45, =59=, 64. "Starch paste," 60. Stearin, 131, 134. Stereo-isomerism, =32=. Stigmasterol, 136. Structural adaptations, =255=. Structural isomerism, =32=. Strychnine, 155, =157=. Substrate, 186. Sucrase (_see_ invertase). Sucrose, 28, =49=, 64. Sugars, 8, 18, 22, 28, 30, 31. Sulfur, 3, 5, =11=, 148. Sulfuretted oils, 147, =148=. Sulfur test, 174. Sunflower-seed oil, 130. Surface boundary phenomena, =231=. Surface energy, 231. Surface tension, 231. "Survival of the fittest," 254. Suspensoids, 206, 214. Suspensions, 206. Synergic foods, 2, 20. Synthesis, 18.

Tagatose, 36, 38, 57. Talose, 36, 38, 42, 57. Tannins, 18, =94=, 97, 99, 100, 127, 208, 224. Tannon group, 96. Terpenes, =147=. Tertiary amines, 152. Tetrapeptids, 167. Tetrasaccharides, =54=. Tetrose, 30, 35. Theobromine, =160=. Theophylline, =160=. Thioglucose, 88. Threose, 35. Thymine, 161, 162. Thymol, 148. Toxins, 13, 239, 240, =245=. Translocation diastase, 191. Trehalase, 51. Trehalose, 49, =50=. Triglycerides, 131. Trimethyl amine, =152=. Trimethyl glycocoll, 143. Triose, 30, 35. Trioxymethylene, 22, 23. Tripeptids, 167. Trisaccharides, 31, =52=. Triticin, 59, =62=. Tryptophane, 169, 171, 177. Tuberin, 176. Turanose, =49=, =53=. Tyndall phenomena, 212. Tyrosine, 115, 168, 177.

Unavailable plant food, 4. Ultrafilter, 215. Ultramicroscope, 203, 204, 205, =211=. Unorganized ferments, 183. "Unsaturated" acids, 132, 138. Uracil, 161, 162. Urease, 190.

Valine, 168. Vanillin, 80, 148. Vegetable bases, 18, =151=. Vicianin, 88. Vicilin, 176. Vignin, 176. Vitamines, 239, 240, 242. Volatile oils, 20, 147.

Water, 3, 21, 22, 23, =224=. Water-soluble B, 243. Waxes, 18, 129, =140=. Weathering, 4. Wood gum, 68. Wool fat, 129. Wound gum, 68, =69=.

Xanthine, =160=. Xanthone, 82, =83=, 102. Xanthophyll, 112, =113=, 121. Xanthopurpurin, 83. Xanthorhamnin, 52, =84=. Xylan, =69=. Xylose, 35, 68, 69. Xylosides, 56.

Yeast, 61.

Zein, 165, 170, 176, 177. Zinc, 13. Zymase, 51, 56, 190, =192=. Zymogens, =198=.

Transcriber's Notes:

The original spelling and minor inconsistencies in the spelling and formatting have been maintained.

The following words have been variably hyphenated in the original: oxy(-)cumarin, tri(-)saccharides, sugar(-)like, mono(-)saccharides, sea(-)weeds, di(-)sodium, foam(-)like, di(-)basic, aldo(-)hexoses, chromo(-)proteins, galacto(-)octose, gluco(-)octose, keto(-)hexoses, ligno(-)celluloses, manno(-)octose, para(-)pectic, di(-)saccharides, poly(-)saccharides. The variable hyphenation has been retained in this version.

Formatting:

Text in italics was marked using underscores (_text_) and bold text using equals (=text=).

The greek characters alpha and beta were marked as [alpha] and [beta]

Triple bonds were marked as [trb] in order to keep the lt1-text. Vertical double bonds are marked with a broken bar ¦.

On page 120 the illustration of the decomposition of chlorophyll a and chlorophyll b could not be displayed due to its complex structure.

On page 147 the incorrect formulas of sitosterol, C_{27}H_{43}OH and stigmasterol, C_{30}H_{49}OH were not changed due to the fact that the pure compounds were first isolated in 1926 after this book was published.

The table below lists all corrections applied to the original text.

p 3: Abderhalden's "Biochemische Handlexicon" -> Handlexikon p 10: with the blood pigment, haematin -> hæmatin p 15: special type, or unusual origin. -> [period added] p 17: that the photo-synthesis -> photosynthesis p 20: Experiments with algae -> algæ p 21: that when algae -> algæ p 26: Experiments," 294 pages, 49 -> [period deleted] p 36: acts as a powerful anaesthetic -> anæsthetic p 40: Die Chemie der Chlorophyll -> Die Chemie des Chlorophylls p 41: many other poly-atomic -> polyatomic p 54: Left parenthesis at C6 of Aldopentose deleted p 55: glucose yeilds -> yields p 60: see pages -> see page p 61: when heated to 82 C° -> 82° C p 65: power of +148.° -> +148°. p 67: attack other dissacharides -> disaccharides p 74: Secalan -> Secalin p 77: Erganzungsband -> Ergänzungsband p 77: Handbuch der Kohlenhydrate," -> [closing quotes added] p 86: Erganzungsband -> Ergänzungsband p 88: has not yet been determined. -> [period added] p 87: by a plane hexagon, thus [Illustration: hexagon]. -> [period added] p 95: C_{21}C_{20}O_{12} -> C_{21}H_{20}O_{12} p 96: blue grapes, _oenin_ -> _[oe]nin_ p 96: glucose + oenidin -> [oe]nidin p 97: reactions of amydalin -> amygdalin p 98: reactions of amgdalin -> amygdalin p 107: Gallic acid, -> [period changed to comma] p 112: Diospyrus -> Diospyros p 114: the following formulas: -> [semicolon changed to colon] p 121: obtained from aetioporphyrin -> ætioporphyrin p 121: that from ætioporphryin -> ætioporphyrin p 122: chlorophylls are fluorescent, -> [period changed to comma] p 122: and red by reflected -> [comma deleted] p 122: properties of these pigments, -> [period changed to comma] p 123: roots of carrots, etc., -> [second period changed to comma] p 123: due to these pigments. -> [period added] p 124: OH groups an addition -> OH groups in addition p 124: Buchner funnel -> Büchner funnel p 126: that it contains leucin -> leucine p 126: leucine and tyrosin -> tyrosine p 134: Willsttäter -> Willstätter p 135: malonic acid -> [space added] p 137: C_{3}H_{5}·COOH -> C_{3}H_{7}·COOH p 138: commercially as a bye-product -> by-product p 146: of the experiment. Microörganisms -> Microorganisms p 154: or through its basic (OH) group -> or through its basic (N) group p 158: oxygenated and sulphuretted -> sulfuretted p 161: Aetherische Oele, Harze, -> [comma added] p 161: F. trans. -> [period added] p 162: HEUSLER, F., [additional comma added] p 164: ergot, and hordeine -> hordein p 171: C_{5}H_{4}N_{4}O_{2}, -> [comma added] p 171: gaunine -> guanine p 177: CH_{3}·CHNH·COOH -> CH_{3}·CHNH _{2}COOH p 179: monoamino-monocarboxylic acids: -> [period changed to colon] p 181: Hystidine -> Histidine p 181: Amadinn -> Amandin p 184: which contains tyrosin -> tyrosine p 184: or a tyrosin-containing -> tyrosine-containing p 185: nitric acid on tyrosin -> tyrosine p 186: acids, or alkalies. -> [period added] p 187: Juglansin, -> [comma added] p 187: of walnut and butternut. -> [period added] p 187: barley. -> [period added] p 192: reactions when caried -> carried p 197: which accelerates the hydyrolysis -> hydrolysis p 198: are further sub-divided -> subdivided p 200: Butryic acid ferment -> Butyric acid ferment p 202: and other microörganisms -> microorganisms p 203: alcohol and carbon dixoide -> dioxide p 205: especially tyrosin -> tyrosine p 206: masses under the ultra-microscope -> ultramicroscope p 212: J. trans -> J., trans. -> [comma added] p 218: chemical nature and dialectric -> dielectric p 231: Dresden and Leipsig -> Leipzig p 231: Leisegang -> Liesegang p 231: Beitrage -> Beiträge p 233: observed under the ultra-microscope -> ultramicroscope p 236: is undoubtedly tetravalent, [period changed to comma] p 237: has a higher dialectric -> dielectric p 239: As in well known -> As is well known p 241: the organism to amother -> another p 242: having a foam-like -> foamlike p 249: Bestimmung der Oberflachenspannung -> Oberflächenspannung p 249: The Role of Diffusion -> The Rôle of Diffusion p 250: SPEIGEL, L., [additional comma added] p 252: of combination with. water -> of combination with water p 255: upon which the micro-organisms -> microorganisms p 258: heavy metals; hydro-carbon -> hydrocarbon p 261: Campferitirin -> Campferitrin p 261: Certain algae -> algæ p 261: certain types of algae -> algæ p 262: mentioned above as "acclimitization"->"acclimatization" p 270: succinic, 127, 128. -> [period added] p 270: metapectic -> meta-pectic p 271: mellisyl -> melissyl p 271: myriscyl -> myricyl p 271: Asymetric -> Asymmetric p 272: Carbon dioxide, 2, 3, 18, 21, 22, 23, -> [comma added] p 273: Curarin -> Curarine p 274: Hesperitin, 79, -> [period changed to comma] p 275: Linayl -> Linalyl p 275: Leucosine -> Leucosin p 275: Lupenine -> Lupinine p 276: Methylethylmallein imide -> Methylethylmalein imide p 276: Mryosin -> Myrosin p 276: Oil of lavendar -> lavender p 276: Oxy-hydroquinone -> Oxyhydroquinone p 277: Photo-chemical action of light -> Photochemical action of light p 277: Proteases, 186, 189, 102 -> Proteases, 186, 189, 192 p 278: Sorbose, -> [period changed to comma]