HOW TO KNOW THE FRESH-WATER ALGAE 



Xanthidium 77 



cristatum var. uncinatum 

 11 



Xanthophyceae 124, 128, 

 134 



XANTHOPHYLL, a yellow 

 pigment of several kinds 

 associated with chloro- 

 phyll, C H O . 



46 56 2 



Xenococcus 176 

 Schousbei 1 76 



Yellow-brown Algae 6 



Zoochlorella 65, 83 



conductrix 65 



parasitica 65 

 ZOOSPORE, an animal-like 



spore equipped with fla- 



gella and usually with an 



eye-spot. 



Zygnema 93; also 3, 92 

 pectinatum 93 



Zygnemataceae 3 



Zygnematales 95 



Zygnemopsis 92 

 decussata 92 

 desmidioides 92 



Zygogonium 93 

 ericetorum 93 



ZYGOSPORE, spore resulting 

 from the union of gam- 

 etes (sex cells); a resting 

 stage. 



211 



