Teleology: the problem of, 30; in inter- 

 pretation of reduction in planarians, 

 44; in interpretation of budding in 

 plants, 231; in interpretation of re- 

 lation between agamic and gametic 

 reproduction in plants, 367, 369. 



Temperature coefficient: of rate of 

 chemical reaction, 68; of length of life 

 of Planaria dorotocephala in cyanides 

 and narcotics, 68; of length of life of 

 sea-urchin eggs, 308; of rate of develop- 

 ment, 308. 



Teratomorphic form, in Planaria doroto- 

 cephala, in, 223. 



Teratophthalmic form, in Planaria doro- 

 tocephala, in. 



Torreya taxifolia, archegonium and egg 



of, 339- . 

 Transmission: in relation to colloids, 26; 



in relation to axial gradients, 209; 

 decrement in, 209, 217, 227; as means 

 of physiological correlation, 217; limit 

 of, 217, 219, 231; in nerves, 218, 230; 

 quantitative effect of, 225; efficiency 

 of, 227. See also Conducting paths; 

 Conductivity. 



Trematode, parthenogenesis in larvae 

 of digenetic, 395. 



Tubularia: simple individual of, 210; 

 reconstitution of, 210; limit of domi- 

 nance in agamic reproduction of, 220; 

 limit of dominance in reconstitution 

 of, 221. 



INDEX 48 1 



Ulothrix, spore formation in, 247. 

 Urocentrum turbo, rejuvenescence of, 

 in agamic reproduction, 141, 142. 



Vacuole, in infusoria, 137. 

 Vacuolization, in plant cells during 



differentiation, 245, 284. 

 Vaucheria: spore formation in, 247: 



conditions -of spore formation in, 250; 



conditions of gamete formation in, 



365- 



Volume and surface. See Surface. 

 Volvox, gametes of, 316. 



Water: in relation to colloids, 24; in 

 relation to growth, 36; production of, 

 in metabolism 37; in relation to senes- 

 cence, 184, 279, 283. 



Winter egg, 390, 404. 



Zamia: spermatozoid of , 334; egg of, 339. 



Zooid: formation of, in Planaria doroto- 

 cephala, 123; formation of, in Steno- 

 stomum, 133; as member of animal 

 colony, 237. 



Zoospore, 247, 252. 



Zygogenesis, 343, 389; gradations be- 

 tween, and parthenogenesis, 410. 



Zygogenic egg: oogenesis of, compared 

 with that of parthenogenic egg, 343; 

 in daphnid Crustacea, 390. 



Zygospore, in algae and fungi, 316. 



