INDEX OF SUBJECTS 



371 



tozoa, 64-67 ; conjugation of, 168 ; nature 

 of, 230, 231 ; position, 276-278. 



Spireme, 27, 47, 77, 193. 



Spirochoiia, mitosis, 62, 63. 



Spirogyra, conjugation, 169; reduction, 

 199. 



Spongioplasm , 17. 



Spontaneous generation, 5. 



Stem-cells, in, 112. 



Sfentor, regeneration, 249, 250. 



Siyloiiychia, senescence. 165. 



Symbiosis, 211. 



Synapla, cleavage, 267, 268. 



Syncytium, 42. 



Telophase, 47. 52. 



Teloblasts, 271, 291. 



Tetrads (Vierergruppen), 179; origin, 186; 

 in .'Iscaris. 1S7 ; in arthropods, 188-193 ; 

 ring-shaped, 18S ; in amphibia, 191, 192; 

 origin l>y conjugation, 199 ; formulas for, 

 186, 193, 200, 201. 



Tka/asse>?ia, fertilization, 143 ; centrosome, 

 228 ; attraction-sphere, 235. 



Thalassicolla, experiments on. 250. 



Tonoplast, 37. 



Toxopneustes, cleavage, 8 ; mitosis, 76 ; 

 ovum, 91 ; spermatozoon. 99; fertili- 

 zation, 146 ; paths of germ-nuclei, 



152; polar bodies, 174; double cleavage, 



260. 

 Trachelocerca, diffused nuclei, 26. 

 .Trophoplasm, 301. 

 Tiibularia, regeneration, 293, 325. 

 Tunicates, egg-axis, 280; cleavage, 281. 



Unicellular organisms, 3 ; mitosis, 62 ; con- 

 jugation, 163; reduction, 198; experi- 

 ments on, 248-252. 

 Unio, cleavage, 272. 



Vacuole, 37. 



Vanessa, ovarian egg, 115. 

 Variations, 9 ; origin of, 329, 330. 



Vaticheria, membrane, 251, 254. 

 Vitelline membrane, 96 ; of egg- fragments, 

 97; formation of, 146; function, 148. 



Volvox, germ-cells, 89, 98. 



Vorticella, conjugation, 167. 



Yellow cells (of Radiolaria), 37, 211. 

 Yolk (see Deutoplasm), 90, 94. 

 Yolk-nucleus, 115, 118. 

 Yolk -plates, 94. 



Zwischenkorper (mid-body), 52. 

 Zygnema, membrane, 252. 

 Zygospore, 169. 



