Classification. i 



1 '> 



coming differentiated after leaving the zoosporaiDgia ; 

 in some species large spherical gonidia are formed 

 intersfcitially and terminal on the braiichlets in im- 

 mense numbers; oogonia monosporous ; wall of 

 mature oospore smooth or variously ornamented with 

 raised bands. 



PijtMum, Pringsh. Jahrb. i. p. 288; Sacc. Syli. 

 vii. p. 270. 



Closely allied to the genus Saprolegnia, in fact the 

 only difference between the two depends on the 

 zoogonidia being fully evolved in the zoosporangium 

 in Saprolegnia, whereas in Pythmm the contents of the 

 zoosporangia escape before the cilia of the zoogonidia 

 are formed. The biological section of mycologists con- 

 sider that the various slight modifications presented 

 during the differentiation of the zoogonidia are of 

 generic importance in the present group ; time will, 

 perhaps, prove whether this idea is correct. 



Pyikium De-Baryanum, Hesse, (figs. 39 — 42). 



Mycelium branched, aseptate or with only an 

 occasional septum ; gonidia spherical, thin walled, 

 terminating short lateral branches, or interstitial, 

 20-30 //-diameter; zoosporangia globose or broadly 

 elliptical, sometimes shortly papillate, terminal or 

 intercalary ; oogonia globose, membrane not per- 

 forated ; oospores globose, exospore thick, smooth, 

 25-35 ijb diameter; antheridia clavate, on very short 

 branches produced immediately below the oogonium, 

 or on distinct branches. 



Pythium De-Baryanum, Hesse, ein Endophytischer 

 Schmarotzer, p. '34 ; Sacc. Syll. vii. n. 924 ; Ward, 



