Index 895 



X 



X chromosome, 187, 697,* 698 (see 



also Heredity) 

 Xanthophyll, 863 {see also Pigments) 

 Xerophthalmia, 474, 769,* 772 

 Xerophyte, 653, 963 

 Xylem, 133, 141,* 145,* 147* (see also 



Tissues) 



Y chromosome, 187, 697,* 698 (see also 



Heredity) 

 Yeast, 125,* 127, 129, 176, 252-254 



pathogenic, 252-254, 253,* 660 

 Yolk granule, 375,* 445* 



gland, 371,* 373, 374,* 378 



plug, 445,* 456 



sac, 451,* 452, 455, 455* 



Zamia, 142,* 203, 204 

 Zea mays, 146,* 209-211 (see also 

 Corn) 



Zein of corn, 89 

 Zernike, 34 

 Zona pellucida, 452 

 Zoogeography, 591 

 Zooglea, 170 

 Zooid, 289* 

 Zoology, 864 



Zoomastigina, 275 (see also Protozoa) 

 Zoosporangium, 125, 154, 157, 161, 

 174, 174* 



Zoospore, 115, 116, 118, 125, 154-157, 

 159, 161, 167, 174, 174* 



Zygapophysis, 424 

 Zygodactyly, 716* 



Zygospore, 124,* 125, 158,* 173, 175, 

 361,* 363 



Zygote, 119, 124, 124,* 125, 130, 136,* 

 138, 143, 150, 157, 158,* 159, 

 161-164, 173, 175, 185-189, 

 193-195, 202, 204, 207, 277,* 

 285,* 361,* 363, 366, 444, 

 708,* 710,* 711 



Zymase, 671, 864 

 Zymogen, 864 

 Zymosis, 864 



