218 SOMK NOVA SroTIAX A(.)rATIC FUXGI. — MOOIIE. 



B. Fungi vvitli a tuycelimn ot' delicate tlireafl-likc hyphai, 

 mostl}' saprophytic, rarely parasitic, living in water or 

 facultatively in moist air ; zoosporangia generally' spheri- 

 cal, resembling in form the oogonia and strongly marked 

 ott from the vegeiative portions of the hypha? ; formation 

 of oospores preceded by a sexual act : conidia present. 



8. Pijthidced'. 



The zoospores are produced in sporangia and are foruied in 

 large numbers by the simultaneous division of the contents of 

 these organs, and, as has been stated, usually escape as swarm 

 spores. In all of the genera of the familj' Saproleyni^iccn', with 

 the exception of Pythiojpsis, Dictyitchus, TJvraiifitothpca and 

 Aplanes, the swarm spores escape as terminally biciliate 

 zoospores, and soon after their escape encyst. After a period 

 of rest, generally a few hours, they escape from their enclosing 

 membranes and pass through a .second swarming stage as more 

 or less kidney shaped laterally biciliate zoospores. After a 

 second encystment germination takes place. I'his phenomenon 

 is referred to as diplanetism. In Phytkiopsis, the second 

 swarming stage is suppressed and germination takes place im- 

 mediately upon the escaping zoospores first coming to rest. In 

 Dictyuchus, the zoospoi-es encyst within the sporangia and 

 finally escape, each by a separate opening through the outer 

 wall, and then appear with lateral cilia. In this genus the first 

 swarming stage is suppressed. The same suppression is also 

 found in Thraasfotheca, and in the genus Aplanes the disappear- 

 ance of the swarming stages is practically complete. Here the 

 spores germinate within the sporangiun), the germ tubes push- 

 ing out through the wall. 



The history of tiie swaiin spores in the famil}^ Leptomitaceoe 

 has not been so completely worked out, but ni the genera 

 Leptoinitiis and Apodacldya, they appear to be diplanetic. 



In the third famih^ of the order, Phthiaeeoe, the swarm 

 spores are monoplane tic. 



