OOMYCETALES II7 



cultivated plants, but where the attempt is made to grow alga^ and 

 other water plants, the fungi of this family occasionally do considerable 

 damage. 



As an example of the first subfamily Olpide.e, may be chosen 

 Olpidiuni endogenum, which lives in the cells of desmids and kills 

 them. The zoosporangium found in desmid cells are oblate spheroids 

 and develop a long tube which projects out of the desmid cell through 

 which the zoospores with a single cilia escape into the water. O. ento- 

 phytum is parasitic in such filamentous algse as Vaucheria, Clado- 

 phora, Spirogyra. Olpidiopsis saprolegnm lives in the elongated 

 cells of Saprolegma,YiXod\xcmg enlargements in the hyphae of the fun- 

 gous host. The swarm spore bores a hole in the cell wall of its host 

 and swells out into a zoosporangium which develops a tube through 

 which the biciliate swarm spores escape into the water. 



The subfamily Synchytrie^ includes most of the fungi which 

 attack the higher plants. Such are Synchytrimn decipiens on the 

 hog peanut (Amphicarpea monoica); S.fulgens on the evening primrose 

 {Oenothera biennis); S. stellarice on Stellaria; S. succiscB on Succisa 

 pratensis; S. taraxaci on dandelion; S. vaccinii causing a gall on cranber- 

 ries, Pycnochytriiini globosum on violet, wild strawberry, blackberry and 

 maple seedlings. P. myosotidis occurs on certain members of the 

 borage and rose families. 



Cladochytrium tenue of the subfamily Cladochytrie^ lives in the 

 subaquatic tissues of the sweet flag, Acorus calamus, flag Iris 

 pseudacorus and a grass, Glyceria aquatica. Its mycelium is widely 

 distributed in the cells of its hosts. Spheric sporangia 18 fx wide and 

 sometimes 66/x are formed as intercalary enlargements of the mycelium, 

 or they are formed at the end of the hyphae, with a colorless supporting 

 cell. They give rise to a short tube-like mouth which breaks out of 

 the host cell. The zoospores are uniciliate. 



Representing the Oochytrie^ is an interesting fungus first fully 

 investigated by Nowakowski, namely, Polyphagus euglencE, which 

 attacks the cells of Euglena, a unicellular animal. Its mycehum con- 

 sists of a. central enlarged portion from which run out in a number of 

 directions branches which end in extremely fine points which penetrate 

 the cells of Euglena. The enlarged central portion develops a swollen 

 tubular outgrowth into which its protoplasm wanders. The contents 

 of this outgrowth then divide into numerous uniciUate swarm spores 



