512 INDEX. 



Vocal sac, 9, 51 ; ligament, 21 Y. 



Vorticella, 359, 368 YEAST, 377388 



Yellow-brown tissue (vide Chlora- 

 *? gogen cells) 



WOOD, 446, 454, 463, 472 2. 



Wood-cells, 473 ZONITES, 241, 248 



Y Zoochlorella (vide Chlorelloids) 



Zooglcea, 409, 412 



XIPHISTERNUM, 69 Zoospores, 391, 393 



Xylem, Bean, 463, 464, 473; Zygapophyses, 56 



Fern, 446, 448, 449, 454 Zygospore, Mucor, 423 ; Spiro- 



Xylem-parenchyma, 455 gya, 401, 407 



CAMBRIDGE: PRINTED BY j. & c. F. CLAY, AT THE UNIVERSITY PRESS. 



