CHYTEIDIINEAE 57 



they pierce and suck its substance by means of haustoria. 

 The rhizoids are branched, and each branch may find a victim. 

 The body of the parasite grows, and part of it bulges into a 

 more or less cylindrical sac or sporangium, into which all 

 the protoplasm passes to divide into a fresh brood of zoospores, 

 which are liberated to repeat the cycle through several 

 generations. 



The passage of all the protoplasm into the sporangium 

 or into the zygote accounts for the empty tubes seen in 

 Fig. 13, 2 and 4. Watched under the microscope in the 

 living state, numerous bright globules, which change in 

 size and arrangement, are seen in the sporangia : they are 

 oil drops: Fig. 4, D ; and Fig. 13, 2 and 5. The nuclei 

 are not so prominent and for the most part are seen only in 

 stained preparations. 



When food becomes scarce conjugation supervenes. In 

 this process a rhizoid of one amoeboid individual joins the 

 body of another, and the protoplasm of the two flow to an 

 enlargement in the joining rhizoid at the point of union to 

 form a zygote or resting spore, which has a thick wall usually 

 studded with short spines. After a resting period it germi- 

 nates forming a sporangium the contents of which subdivide 

 into zoospores. The oil-drop is absent from the zoospores 

 of some chytridians. 



The zoospores of Polyphagus are phototaxic as are the 

 Euglenae it feeds on (de Bary). 



Wager found that cultures of Euglena obtained from a 



