INDEX. 



5'3 



Willow family, 494 



Wind, 471 



Wintergreen, 499; leaf of, .43 



Witch-hazel, 496 



Wolffia, 28 



Woodland formation, 470 



Xerophytes, 467 

 Xylem/50, 52, 360, 361, 363 

 Xylogen, 92 

 Xyridales, 493 



Yeast, 216; fermentation of, 115, 



116 

 Yucca, 480, 493 



Zamia, 313, 316, 457 

 Zoogonidia, 143, 149, 178-184 

 Zoospore, 149, 154 

 Zygomycetes, 215 

 Zygospore, 2, 138-140, 157, 160, 179, 



180 

 Zygote (zy'gote), 138, 179 



