THE ASEPTIC CULTIVATION OF MYOETOZOA. 59 



form Plasmodia, says, '' The inference becomes almost a cer- 

 tainty after watching the specimens under cultivation ;" but 

 he did not actually see them fuse. 



Strasburger (26) also describes the fusion of the zoospores 

 to form Myxamoeba. 



The writer has not been fortunate enough to observe the 

 fusion of the zoospores, but the accuracy of the observations 

 of such competent observers as Cienkowski, Strasburger, 

 Lister, and others can hardly be doubted. In the cultures, 

 as the writer has studied them, however, he does question 

 whether the fusion of the zoospores is the chief mode by which 

 the Plasmodia grow. 



If a few drops of a culture containing microcysts of Stemo- 

 nitis, with suitable bacteria, be inoculated in a flask con- 

 taining sterilised water, with milk 2 per cent., the bacteria 

 multiply at the expense of the milk. Within two or three 

 days the fluid loses the slight opalescent appearance which it 

 had, and on microscopic examination there are no longer milk 

 globules present. I think, from our knowledge of bacteria, 

 we can conclude that at least a portion of the milk has been 

 consumed by them. During this time the zoospores have 

 nultiplied by division ; they feed on the bacteria, and possibly 

 some elements of the milk which the bacteria may not have 

 appropriated. In a few days the zoospores begin to encyst, 

 and by the end of the second week the majority of the zoospores 

 are encysted, while a smaller number remain active. If control 

 cultures are made from the flask, it will be found that there are 

 not near so many bacteria present as there would be in a flask 

 containing a similar medium inoculated with the bacteria 

 alone which grow with the zoospores. In from ten to fourteen 

 days small plasmodia may appear; they increase in numbers 

 and in size, and later large plasmodia are present. 



In cultures made in flasks containing hay, with milk 2 per 

 cent, in hay infusion, essentially the same changes take place, but 

 the hay interferes somewhat with the examination. If examined 

 about the end of the second week one finds bacteria, encysted 

 zoospores, active zoospores, and a few small plasmodia. The 



