476 



INDEX 



Water Lily, 108 



Weismann, 267, 404 



Whale, 116; skeleton of flipper, 



352 



Wheat, 263 

 Wood, 88 

 Working hypothesis, 5, 396 



X chromosome, 292, 293, 377 

 Xylem, 60, 76, 81, 87 



Yeast, SIS, 310 

 Yolk, 238 



Zoogeography, 368 



Zoology, 3, 4 



Zygote, 32, 95, 98; chromosomes 

 in, 289, 290, 293; in genetics, 

 275-284; organization of, 251- 

 260 



