58 



PROTISTS AND DISEASE 



sewage-farm were heavily infected ; their normal grey- 

 green colour changing first to yellow and finally to a dark 

 brown. The same author has given a full account of the 

 cytology of Polyphacjus. The zoospore germinates as soon 



FlG. 14. POLYPHAGUS EUGLENAE, NUCLEAR PROCESSES. A, ZOOSpOre 



with its nucleus and fat-drop surrounded by a chromidium ; A 1 , 

 young plant soon after germination, nucleus and chromidium ; 

 B, beginning of vegetative spore -formation, half the nucleus is in 

 the sporangial diverticulum ; C, vegetative sporangium with 

 4 resting nuclei ; C 1 , a sporangial nucleus at metaphase ; D, conjuga- 

 tion, some of the chromidial granules of the female (upper) gamete 

 have entered the swelling which becomes the resting spore or zygote ; 



E, zygote, with 2 small nuclei and their chromidia. 

 after H. Wager. 



Reduced to f, 



as it conies to rest ; in external form it resembles the common 

 protozoon Actinophrys, a Heliozoon, and having a well- 

 marked chromidium it is very like a Khizopod, Fig. 14, A 1 . 



