CHLOROCHYTRIUM. 



549 



Chlorochytrium lemnae Cohn.i The zygozoospores have 

 four cilia and swarm for a short time in water. On plants of 

 Lemna trimdca, the ciliated end becomes applied to the epidermis 

 at the place where two cells are in contact, the zoospore becomes 

 spherical, forms a membrane, and comes to rest (Fig. 324). It 

 remains resting for a day or two, and assimilates so that a 

 starch-grain is formed inside it. Next, a transparent process is 

 given off which finds its way between the epidermal cells, widens 

 out, and absorbs the cell-contents, while the portion of the algal 



. Fig. 324. — ChlovochytHum lemnae. a, 6, c, Ger- 

 miuating spores penetiating through the epi- 

 dermis and between the cells of the parenchyma. 

 A surface view shows the germinating spores 

 from above. (After Cohn.) 



Fig. 325. — Chlorochytrium lemnae 

 in Lemna tnsulca. a, Mature ; b, 

 young ; c, discharged sporangia. 

 (After Klebs.) 



cell remaining outside becomes filled with cellulose and forms a 

 firm button-like process. The young alga continues to make 

 its way between the cells into the intercellular spaces of the 

 subepidermal layers of parenchyma, preferably taking up its 

 quarters iu the thin anterior margin of the thalloid shoot, 

 and avoiding the larger air-spaces. The zoospores are formed 

 by repeated division of the plasma of the original cell ; they 

 are enclosed in a gelatinous mass which swells and ruptures 

 the membranes of the alga as well as the tissue of the Lemna. 



'Cohn, Beitrage zur Biolorjie d. nied. Organismen; Klebs, Botan. Zeitung, 1881. 



