INDEX 



583 



Vinegar-eel, 344. 

 Viviparous development, 63. 

 Vivisection, 25. 

 Volvox, 318. 

 Vorticella, 317. 



,W 



Waste, in living matter, 44. See also 

 excretions. 



Water, 8; as excretion, 114, 509; in 

 germination, 154; hygiene, 529; 

 in leaf, 95 ; need of, 95 ; in organ- 

 isms, 10, 44 ; in roots, 92 ; in soil, 

 87 ; in stems, 94 ; use of in plant, 

 97 ; in transportation, 130. 



Water-flea, 374. 

 Wood, 184. 

 Wood-lice, 373. 

 Work, see energy. 

 Worms, 340-354. 



Yeast, 268. 

 Yellow fever, 394. 

 Yolk, 447. 



Z 



Zoology, definition of, 2. 

 Zygospore, 255. 



