328 
Structure,63; differentiation of, 64. 
Struggle for existence, 116, 
Stylops parasitizing Polistes (illus.), 
192. : 
Sub-species, definition of, 282. 
Surroundings, adaptations 
cerned with, 143. 
Swallow-tail butterfly, chrysalid 
of (illus.), 205. 
Sword-fish, metamorphosis of (il- 
lus.), 99. 
Symbiosis, 172, 175. 
Syngamus trachealis (illus.), 60. 
Systematic zodlogy, 64. 
con- 
Tactile organs, 226. 
Tactile papilla of skin of man (il- 
lus.), 227. 
Tadpole, 94. 
Tenia solium (illus.), 183. 
Tailor-bird, nest of (illus.), 268. 
Tape-worm (illus.), 183. 
Taste buds of calf (illus.), 229. 
Taste organs, 228. 
Taste, sense of, 228. 
Temperature a barrier to distribu- 
tion, 290; a condition of animal 
life, 108. 
Tentacle, 37. 
Termite, 158, (illus.), 159. 
Terrifying appearances, 212. 
Thalessa lunator (illus.), 191. 
Toad, egg of (illus.), 79; horned 
(illus.), 181; metamorphosis of, 
94, (illus.), 95. 
Torpedo (illus.), 135. 
Tortoise, embryonic stages of (il- 
lus.), 87. 
Touch, sense of, 226. 
Trap-door spider nest (illus.), 261. 
Tree-hoppers mimicking leaf-cut- 
ting ant (illus.), 220. 
ANIMAL LIFE 
Tree-toad (illus.), 145. 
Tremea columba (illus.), 191. 
Trichechus latirostris (illus.), 277. 
Trichina spiralis (illus.), 184. 
Tripoli, 19. 
Trochilus rufus, nest of (illus.), 
265, 266. 
Trout, rainbow, head of (illus.), 
145. 
Two Ocean Pass (illus.), 287. 
Tunicate (illus.), 194. 
Turret-spider, nest of (illus.), 262. 
Typhlichthys subterraneus (illus.), 
282. 
Uncinaria, killing fur-seal pups 
(illus.), 186. 
Uria lomvia arra (illus.), 165. 
Urolophus goodez (illus.), 133. 
Vacuole, 10; contractile, 10. 
Variety, definition of, 282. 
Vedalia and Icerya, 121. 
Vertebrates, early stages in devel- 
opment of (illus.), 87; nest-mak- 
ing habits of, 264; parasitic, 193. 
Vespa (illus.), 162; nest of (illus.), 
163. 
Vestigial organs, 147. 
Viceroy butterfly mimicking Mon- 
arch butterfly (illus.), 219. 
Voice, 236. 
Volvocine, 24. 
Volvox, 28. 
Volvox globator (illus.), 29. 
Volvox minor (illus.), 29. 
Vorticella, 12. 
Vorticella microtoma, (illus.), 12. 
Walking-stick insect (illus.), 209. 
Warning colors, 212. 
Walrus, Atlantic (illus.), 298. 
