Part 2

FIG. PAGE 1. Schematic Longitudinal Section of the Human Body 4 2. Human Skeleton 7 3. Skeleton of an Ox 9 4. Bending of the Arm by Contraction of the Biceps Muscle 10 5. Diagram to explain the Action of the Motor and Sensory Nerves 11 6. Diagram of the Course of the Circulation 13 7. Life History of the Small-winged Gall-fly (_Andricus terminalis_) 15 8. Diagram of a Fish’s Heart 18 9. Diagram of a Mammal’s Heart 20 10. Diagram of a Reptile’s Heart 20 11. Diagram of a Frog’s Heart 21 12. Vertical Section of a Human Grinding Tooth 22 13. Crown of an Ox’s Grinder 22 14. Skull of Domestic Cat 25 15. Pine Marten (_Mustela martes_) 27 16. Skull of Mole 30 17. Common Shrew (_Sorex vulgaris_) 31 18. Skeleton of Bat 34 19. Skull of Squirrel 35 20. Abnormal Tooth in Hare 37 21. Hamster (_Cricetus frumentarius_) 38 22. Long-tailed Field Mouse (_Mus sylvaticus_) 40 23. Upper Back Teeth of Brown Rat 41 24. Upper Back Teeth of Water Vole 41 25. Southern Field Vole (_Arvicola arvalis_) 43 26. Skull of Sheep 44 27. Development of Roebuck Antlers 45 28. Wing of Buzzard 50 29. Section through Bird’s Egg 51 30. Eagle Owl (_Otus maximus_) 52 31. Head and Foot of Falcon 53 32. Golden Eagle (_Aquila chrysaëtus_) 54 33. Barn Owl (_Strix flammea_) 55 34. Cuckoo (_Cuculus canorus_) 56 35. Goatsucker (_Caprimulgus europæus_) 58 36. Head of Rook (_Corvus frugilegus_) 60 37. Head of Bullfinch (_Pyrrhula vulgaris_) 62 38. Nightingale (_Daulias luscinia_) 65 39. Wood Pigeon (_Columba palumbus_) 66 40. Capercailzie (_Tetrao urogallus_) 68 41. Pheasant (_Phasianus colchicus_) 69 42. Woodcock (_Scolopax rusticola_) 70 43. Crested and Little Grebes (_Podiceps cristatus and minor_) 71 44. Grey Goose (_Anser cinereus_) 72 45. Herring Gull (_Larus argentatus_) 74 46. Common Lizard (_Lacerta agilis_) 75 47. Adder (_Pelias berus_) 76 48. Grass Snake (_Tropidonotus natrix_) 77 49. Blindworm (_Anguis fragilis_) 78 50. Great Crested Newt (_Triton cristatus_) 79 51. Common Frog (_Rana temporaria_) 80 52. Natterjack (_Bufo calamita_) 81 53. The Perch (_Perca fluviatilis_) 82 54. Wood-borer (_Sirex_) 83 55. Centipede (_Scolopendra morsitans_) 84 56. Ground Beetle, showing Nervous System 84 57. Disarticulated Grasshopper 85 58. Head and Mouth-parts of a Ground Beetle 87 59. Leg of Ground Beetle 88 60. Stages of Silkworm Moth (_Bombyx mori_) 88 61. Stages of Hornet (_Vespa crabro_) 89 62. Migratory Grasshopper (_Acrydium migratorium_) 90 63. Looper Caterpillar 90 64. False Caterpillar 90 65. Stages of Cockchafer (_Melolontha vulgaris_) 91 66. Larva of a Weevil 92 67. Stages of Aphis-eating Fly (_Syrphus pyrasti_) 92 68. A Ground Beetle (_Carabus auronitens_) 95 69. Corn Ground Beetle (_Zabrus gibbus_) and larva 95 70. A Rove Beetle (_Staphylinus erythropterus_) 96 71. Black Burying Beetle (_Silpha atrata_) and larva 96 72. Antennæ of Cockchafer 99 73. Abdomens of Common and Horse-chestnut Cockchafers 100 74. Skipjack (_Agriotes lineatus_) 102 75. Skipjack about to spring 103 76. Grain-plants sown deep and shallow, to show Wireworm attack 104 77. Bean Beetle (_Bruchus rufimanus_) 106 78. Pea Weevil (_Sitones lineatus_) 107 79. Mouse-tooth Weevil (_Baridius chloris_) and larva 108 80. Turnip Gall Weevil (_Ceutorhynchus sulcicollis_) 109 81. Colorado Beetle (_Chrysomela decemlineata_) 111 82. Stages of Colorado Beetle 112 83. Cloudy Tortoise Beetle (_Cassida nebulosa_) 113 84. Rape Flea Beetle (_Psylliodes chrysocephalus_) 114 85. Stages of Seven-spotted Lady-bird (_Coccinella septempunctata_) 118 86. Stages of Common Lace Fly (_Chrysopa vulgaris_) 122 87. Head of Honey Bee (_Apis mellifica_) 124 88. Common Wasp (_Vespa vulgaris_) and nest 127 89. Common Sand Wasp (_Ammophila sabulosa_) 129 90. Stages of Yellow-legged Ichneumon Fly (_Microgaster glomeratus_) 133 91. Turnip Saw-fly (_Athalia spinarum_) and caterpillars 135 92. Head of Butterfly 136 93. Scales from Butterfly’s Wing 136 94. Stages of Peacock Butterfly (_Vanessa io_) 138 95. Stages of Cabbage White (_Pieris brassicæ_) 139 96. Garden White (_Pieris rapæ_), male 141 97. Garden White, female and caterpillar 141 98. Green-veined White (_Pieris napi_) 142 99. Dart or Turnip Moth (_Agrotis segetum_) and caterpillar 143 100. Stages of Cabbage Moth (_Mamestra brassicæ_) 146 101. Grass Moth (_Charæas Graminis_) and caterpillar 150 102. Stages of Silver Y Moth (_Plusia gamma_) 151 103. Hop Snout Moth (_Hypena rostralis_) 153 104. Mother-of-Pearl Moth (_Botys margaritalis_) and larva 155 105. Fawn-coloured Pea Moth (_Grapholitha nebritana_) 156 106. Larch Moth (_Coleophora laricella_) 157 107. Wings of a Bug 159 108. Bean Aphis (_Aphis papaveris_) 160 109. Corn Thrips (_Thrips cerealium_) 163 110. Wheat Midge (_Cecidomyia tritici_) 165 111. Barley attacked by Hessian Fly 167 112. Larvæ of Wheat Midge (_Cecidomyia tritici_) 169 113. Stages of Daddy Longlegs (_Tipula oleracea_) 171 114. Rain Breeze Fly (_Hæmatopota pluvialis_) 174 115. Caterpillar Fly (_Tachina fera_) 175 116. Turnip infested by Cabbage Fly (_Anthomyia brassicæ_) 177 117. Ribbon-footed Corn Fly (_Chlorops tæniopus_) 179 118. Stages of ditto 181 119. Wheat Plant distorted by winter generation of ditto 181 120. Stages, etc., of Frit Fly (_Oscinis frit_) 183 121. Stages of Horse Bot Fly (_Gastrus equi_) 190 122. Horse Louse (_Hæmatopinus macrocephalus_) 194 123. Common Snake Millipede (_Julus terrestris_) 195 124. A Spider (_Salticus scenicus_) 196 125. Mange Mite of the Pig (_Sarcoptes scabiei, var. suis_) 197 126. Ditto 198 127. The Dog Tick (_Ixodes ricinus_) 203 128. Diagrammatic transverse section through a Thread Worm 210 129. Tail of male _Strongylus armatus_ 213 130. Encapsuled Muscle Trichinæ in flesh 217 131. Male Intestinal Trichina 217 132. Rye Plant in the later stage of the Eelworm Disease 222 133. Ear Cockles of Wheat 225 134. Stages of Beet Eelworm (_Heterodera Schachtii_) 226 135. _Tænia saginata_ 232 136. Common Tapeworm (_Tænia officinalis_) 234 137. Tapeworm Larva (_Tænia solium_) 234 138. Types of Bladder-worm 235 139. Measle of _Tænia solium_ 235 140. Measles in Pork 236 141. Liver Fluke (_Distoma hepaticum_) 241 142. Life History of Liver Fluke 242 143. Diagrams of Molluscs 246 144. Grey Field Slug (_Limax agrestis_) 249 145. Common Starfish (_Asterias rubens_) 252 146. Freshwater Polype (_Hydra_) 254 147. A Jellyfish (_Pelagia noctiluca_) 254 148. A Sea Anemone (_Sagartia nivea_) 254 149. Proteus Animalcule (_Amœba_) 255

ZOOLOGY.

INTRODUCTION.

I. Subdivision of the Animal Kingdom.

There are animals so like one another that they are given the same name. Such animals are ranked in the same _species_. Animals which differ so much that they have to be referred to different species, but which notwithstanding agree in the majority of their characters, especially the most important ones, are placed in the same _genus_. Hare and rabbit, or horse and donkey, are reckoned as different species of the same genus. Genera resembling one another are united into a _family_; thus, the pine marten and the beech or stone marten both belong to the _Marten genus_ (Martes), while the weasel and stoat are different species of the _Weasel genus_ (Mustela); but these two genera are so similar that they are both placed in the same family, _i.e._ the _Weasel family_ (Mustelidæ). Nearly related families together build up an _order_. Thus, the Weasel family, Dog family, Cat family, etc., collectively constitute the _order of Carnivora_, characterized, speaking generally, by the same kind of teeth, claws, habits, and food. Several related orders are united into a _class_. Thus, for example, carnivorous animals (Carnivora), ruminating animals (Ruminantia), gnawing animals (Rodentia), etc., constitute different orders of the _class of Sucklers_ (Mammalia); while birds of prey (Raptores), pigeons (Gyrantes), and poultry (Rasores), are included in a second class, that of _Birds_ (Aves). But both Birds and Mammals have a skeleton, of which the chief support is the backbone; on this account they are placed in a larger subdivision, the _sub-kingdom_ of Backboned animals (Vertebrata); while snails are grouped under the sub-kingdom of _Molluscs_, millipedes and centipedes under that of _Jointed-limbed animals_ (Arthropods).

In this way the animal kingdom is divided into _sub-kingdoms_, the sub-kingdoms into _classes_, the classes into _orders_, the orders into _families_, the families into _genera_, and the genera into _species_. Animals of the same species which differ from one another in more or less constant characters, belong to different _races_ (domestic or geographical races).

There are many species of animals the external features of which are well known to ordinary folk, and which therefore possess a definite English name, but a much larger number, of the smaller forms especially, have no English name. It is, therefore, necessary to devise new names for these species. The English names, however, are liable to cause great confusion, since in different districts the same name is often applied to widely different animals. Besides this, distinct names have usually been given to successive stages in the life history of the same form: “wireworms,” for example, are the young state of the “click beetle.”

By using the scientific method of naming invented by Linnæus, confusion is made impossible. The Latin names of this naturalist have the great advantage that they not only give a perfectly distinct name to any particular species, but also at the same time show the genus to which it belongs. Each kind of animal possesses, in fact, two names; just in the same way as every person possesses at least two names, a Christian name and a surname. The generic name comes first, and is, of course, common to all animals of the same genus. The second name is the specific one, and belongs exclusively to animals of the same species. The hare and rabbit, for example, are both included in the genus _Lepus_. The Latin name of the first is _Lepus timidus_; that of the second, _Lepus cuniculus_. Horse = _Equus caballus_; ass = _Equus asinus_.

II. Review of the Structure and Vital Phenomena of Animals.

I select as a point of departure the human body, and the bodies of domestic animals, because my readers are best acquainted with these.

The limbs consist, beginning on the outside, of skin, flesh, and bone. The same parts can also be distinguished in the head, neck, and trunk; but in these divisions of the body they enclose a cavity, the _body-cavity_, which, again, contains various parts (“organs”), which are not everywhere attached to the body-wall. Fig. 1 represents a longitudinal section through the body. The skin is represented by a line, flesh and internal lining are shaded, while the bones are black. These parts form together the _body-wall_. In front the body-wall encloses a cavity, the body-cavity (_Kh._), which in Mammals is divided into two sections (thoracic cavity, _Bz.h_, and abdominal cavity, _B.h._) by the _midriff_ (diaphragm). In the thoracic cavity are found the lungs and heart (_H_), also most of the gullet or upper part of the gut; the abdominal cavity contains the remainder of the often much-coiled gut, which in one place widens into the stomach (_M_), also the kidneys, spleen, and parts connected with the gut (_e.g._ the liver). The cavities are bounded behind by the backbone (vertebral column), which is made up of many flattened vertebræ. The uppermost vertebra supports the skull, which encloses a _cranial cavity_ (_Sch.h._) continuous with a _vertebral canal_ bounded by the vertebræ. Cranial cavity and vertebral canal form together a second body-space, in which are contained the brain and spinal cord.

We will now consider the individual parts of the body, beginning with the _skeleton_. The axis of the skeleton is formed by the vertebral column (spine), which is composed of flat bones, the _vertebræ_. A vertebra usually consists of (1) the body, which occupies the front; (2) the arch, which possesses several projections or processes (neural spine, transverse processes, articular processes) and encloses the vertebral canal (_W.h._). All mammals have seven neck or cervical _vertebræ_ (Fig. 2, 1); while the number of the remaining vertebræ varies according to the species. The cervical vertebræ, which support the head, are followed by the dorsal or _thoracic vertebræ_ (12 in man, Fig. 2, 2), and these by the strong loin or _lumbar vertebræ_ (5 in man, Fig. 2, 3). Cervical, thoracic, and lumbar vertebræ are movable, but, in man, the last-named are followed by five vertebræ immovably united together to make up the _sacrum_, and these again by tail- or _caudal vertebræ_. Man has four such vertebræ, all poorly developed, and fused with one another (Fig. 2, 5); but in many animals there are a large number, movably united to make up a tail.

The ribs, which in mammals bound the chest, are jointed to the thoracic vertebræ. Man has 12 pairs of ribs; each rib consists of a bony part behind and a gristly (cartilaginous) part in front. The so-called true ribs (Fig. 2, 14) [the upper pairs] are movably united with the breast-bone, but this is not the case with the false ribs (Fig. 2, 15).

In the head we distinguish the brain-case or _cranium_, and the skeleton of the _face_. The first contains the cranial cavity in which the brain is enclosed. We distinguish—2 frontal bones (fused together in man, Fig. 2, 6); 2 parietal bones (7); 2 temporal bones (8); an occipital bone (9) composed of several pieces fused together, perforated by the foramen magnum [where brain and spinal cord unite], and bearing two elevations or condyles [for effecting union with the backbone]; and the sphenoid and ethmoid bones which make up the base of the cranium. The facial skeleton consists of the framework of the jaws and palate, and, together with some of the cranial bones, bounds the cavities in which the eyes are contained (orbits), and the nasal cavities. It consists of the maxillary bones (Fig. 2, 12), the premaxillary bones (Fig. 3, 7,—in man these 4 bones are fused together into one piece), the nasal bones, the lachrymal bones, the ploughshare bone (vomer), the turbinated bones, the cheek-bones (or malars, Fig. 2, 11), the palate-bones, and the lower jaw (Fig. 2, 13). (The last originally consists of two symmetrical halves.)

The upper and lower limbs are built on the same type, and therefore consist of corresponding parts (cp. Fig. 2). The more similar the functions of the two pairs, the closer their resemblance. In the ox they are much more alike than in man; in the bird, on the contrary, the similarity is much less. A distinction can be drawn in both limbs between the bony girdles (shoulder-girdle and hip-girdle), which serve for union with the trunk-skeleton, and the different subdivisions of the limbs themselves. I place side by side the parts of the arm and leg of man.

ARM. │ LEG. I. Shoulder-girdle, consisting │ I. Hip-girdle, consisting of: of: │ Shoulder-blade (Scapula) (Fig.│ Hip-bone (Ilium) (24). 2, 17). │ Collar-bone (Clavicle). │ Pubis. Coracoid process (of Scapula).│ Rump-bone (Ischium). II. Upper arm: │ II. Thigh: Upper arm-bone (Humerus) (18).│ Thigh-bone (Femur) (25). III. Fore arm: │III. Leg: Radius (19). │ Shin-bone (Tibia) (26). Ulna (20). │ Clasp-bone (Fibula) (27). IV. Hand: │ IV. Foot: Two rows of wrist-bones │ Two rows of ankle-bones (Carpal bones) (21). │ (Tarsal bones) (28). Metacarpal bones (22). │ Metatarsal bones (29). Finger-bones (Phalanges) (23).│ Toe-bones (Phalanges) (30).

The differences between arm and leg are explained by their different uses. The bones of the leg, used to support the human body, are firmer and thicker, but less movable than those of the arm, which is employed in grasping. Consequently the union between the hip-girdle and the trunk-skeleton is firmer than that of the shoulder-girdle. The radius can rotate upon the ulna, so as to completely turn the hand over; a similar twisting of the foot would not be of use, and cannot be effected. The leg has a knee-pan (patella) (Fig. 31), with which there is no bone in the arm to correspond. In the foot the toes are short, and the remaining parts long; for instance, one of the tarsal bones, the calcaneum (heel-bone), is strongly developed and projects behind (28*). In the hand, the digits are relatively long, and since the tip of the thumb can be made to touch the tips of all the fingers, are admirably adapted for grasping.

The number of fingers or toes is at most five, but may be less. The horse has a single digit to each limb; the ox, two well developed and two remaining as rudiments; the pig, two large and two small; while the dog has four toes in the hind foot, five in the fore foot.

Man walks on the sole of the foot. Some other animals (dog, cat) on the toes; others again (horse, ox, pig), on the tips of the toes. In the last case there is not simply a horny structure (nail or claw) on the upper side of the toe, but a hoof sheathing the whole of its tip. In many animals the thigh and upper arm are drawn close up to the body, so that the limbs appear quite different from those of man. (Compare Fig. 2 with Fig. 3.)