THE ASKPTIC CULTIVATION OF MYCETOZOA. 57 



numerous tliau wlien a good many of the stalks projected. 

 The time from the planting of the cultures until the sporangia 

 form varies considerably. 



Cultures of S tcmonitis A, B^ and C formed sporangia as 

 early as the thirtieth, and as late as the seventy-sixth day. 

 Two cultures made from the same parent culture in the same 

 media developed sporangia on the thirty-second and seventy- 

 sixth day respectively. 



As a rule but one set of sporangia developed in the same 

 culture. Sporangia do not develop in all the cultures ; at 

 times large plasmodia form on the hay and degenerate without 

 forming sporangia. 



Physarum ciner cum formed sporangia from the twenty- 

 second to the sixty-fourth day. 



Didymium farinaceum formed sporangia on the dried 

 leaves on the fifty-seventh day. 



jLthalium septicum formed large plasmodia about the 

 fifty-fifth day, remained on the side of the flask for about ten 

 days, and then degenerated without forming sporangia. 



Plasmodia under natural conditions leave their moist or wet 

 habitat, crawl to the surface when it is dry, and they are ex- 

 posed to the light. In some of my cultures the formation of 

 the sporangia seems to have been delayed by keeping the 

 culture in the dark ; some of the cultures were kept in the 

 dark six weeks, and after being in the light for several weeks 

 formed sporangia. 



The zoospores develop readily in the oven at 37'' C, but no 

 sporangia formed in any of the cultures. The absence of light 

 may have had something to do with the result. 



Time of the Day at which the Sporangia develop. 



De Bary (8) studied the formation of the sporangia of 

 Physarum sulphurcum, Didymium serpula,-iEthalium 

 septicum, and Stemonitis ferruginea, and found that 

 usually the sporangia began to form in the afternoon or late 

 evening, and the development was completed in some cases by 



