INDEX 
Colon, 68. 
Colonial jelly-fishes, 45; Protozoa, 
24, 
Colony, 31. 
Color, 222, 
Coloration, alluring, 216, 
Colors, warning, 212. 
Commensalism, 172, 173. 
Communal life, 168; advantages 
of, 170. 
Communities, animal, 149, 
Conditions, primary, of animal 
life, 106, 
Conjugating cells, 28. 
Conjugation, 11, 27, 55, 
Contractile vacuole, 10. 
Coral, brain, 45; island (illus.), 
44; organ-pipe (illus.), 45; red, 
45. 
Corals, 37-43. 
Corynolophus reinhardti (illus.), 
124, 
Cottony cushion scale (illus.), 142. 
Courtship, instincts of, 248. 
Crab, metamorphosis of (illus.), 97; 
with sea-anemone (illus.), 177. 
Cray-fish, auditory organ of (illus.), 
233. 
Cricket, auditory organ of (illus.), 
234, 
Cricket, mole (illus.), 146. 
Crinoid (illus.), 305. 
Crop, 71. 
Crowd of animals, 114. 
Crustaceans, adults and larve 
(illus.), 195. 
Cteniza caltfornica, nest of (illus.), 
261. 
Cyanocitia cristata (illus.), 138. 
Cycle, life, 78. 
Cypselurus (illus.), 181. 
Cytoplasm, 3. 
22 
321 
Dead-leaf butterfly (illus.), 211. 
Death, 103. 
Deep-sea angler (illus.), 124, 
Deer, horns of (illus.), 148, 
Defense of the young, 187, 
Degeneration, causes of, 197, 198; 
human, 200; through quiescence, 
193. 
Desiccation, 104. 
Development, 78; continuity of, 
83; divergence of, 84; embry- 
onic, 80; first stages in (illus.), 
81; laws of, 86; metamorphic, 
90; of flounder (illus.), 100; of 
locust, (illus.), 91; of vertebrates, 
(illus.), 87; post-embryonic, 80; 
significance of facts of, 89, 
Diapheromera femorata (illus.), 
209. 
Differentiation, 41; of structure, 
64, 
Dimorphism, 42; sex, 58. 
Diodon hystriz (illus.), 134. 
Dismal Swamp fish (illus.), 282. 
Distribution, character of barriers, 
to, 288; geographical, 272; in- 
fluenced by climate, 291; laws 
of, 274; modes of, 296; monn- 
tains a barrier to, 293; of Cana- 
dian Skipper butterfly (illus.), 
278; of clouded Skipper butter- 
fly (illus.), 278; of Hrynnis 1 ani- 
tobe (illus.), 273; sea a barrier 
to, 288; temperature a burrier 
to, 290. 
Diverticula, 74. 
Division of labor, 22, 168. 
Dog, pointer (illus.), 256. 
Dragon-fly, eye of (illus.), 239. 
Duck, family (illus.), 137. 
Duoder am, 68, 
Duration of life, 101, 
