THE FUNGI 



153 



Of the forms attacking the higher plants, the commonest belong 

 to the genus Synchytrium. S. papillatum is sometimes very common 

 in California upon Erodium cicutarium, whose leaves become con- 

 tracted, and covered with minute brilliant crimson pustules, caused 

 by the enlargement of the epidermal cells which are infested by the 

 parasite. The reproduction is by zoospores, much as in Chytridium, 

 but no sexual organs are known. 



FIG. 117. A, Chytridium, olla, zoosporangium, sp, attached to the ob'spore of 

 (Edogonium sp. (X 400). B, Olpidium pendulum, growing upon a pollen-grain of 

 Pinus, sp. C-E, Polyphayus Euglense. C, germinating zoospore attached to a 

 resting-cell of Eugleua, a (X 275). D, zoosporangium (X 325). E, zoospore 

 (X450). F, conjugating gametes of Zygochytrium aurantiacum (X 325). (B, 

 after ZOPF; C-E, after NOWAKOWSKI ; F, after SORO KIN.) 



Order II. Saprolegniineae (Humphrey, 10) 



The most important family of the Saprolegniineae is the Saproleg- 

 niaceae, or Water-moulds. These are aquatics, much resembling in 

 appearance a colorless Vaucheria. The commonest ones belong to 

 the genus Saprolegnia (Fig. 118), which occur as saprophytes upon 

 the bodies of dead insects and crustaceans. One species, S. ferax, is 

 a very destructive parasite, attacking the eggs and young of fishes, 

 which are thus destroyed in great numbers. 



The plant consists of delicate branching hyphse which send rootlets into the 

 body of the animal upon which it is growing. The protoplasm, which lines the 

 cell-wall, contains many small nuclei, and often shows active streaming move- 

 ment. Except for the absence of chromatophores, there is a strong resemblance 

 to the filaments of Vaucheria. 



Reproduction. The plants multiply rapidly by the formation of zoospores, 

 which are formed in terminal club-shaped sporangia (B-D), much like those of 



