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Vol. LI. September, 1926. No. 3. h 



L I 



BIOLOGICAL BULLETIN 



OBSERVATIONS ON THE RELATIONSHIP BETWEEN 



A RED TORULA AND A MOLD PATHOGENIC 



FOR DROSOPHILA MELA NOG ASTER. 



MARTIN FROBISHER, JR., Sc.D. 



FROM THE DEPARTMENT OF PATHOLOGY AND BACTERIOLOGY, JOHNS HOPKINS 



UNIVERSITY, BALTIMORE, MD. 



In cultivating D. melanogaster at the Institute for Biological 

 Research at Johns Hopkins University, a difficulty arose during 

 the summer of 1925, which at times interfered with the growth 

 of the flies. This difficulty was the appearance, in the flasks 

 used for cultivation, of a growth that resembled the ordinary 

 blue-green Penicillium but which appeared to form on the sur- 

 face of agar, a thick, tough, basement membrane of a bright 

 lemon-yellow color. This growth was apparently very obnoxious 

 to the flies for they died in large numbers soon after being put 

 into jars containing it. The phenomenon was brought to the 

 attention of the author and the following studies made. 



Microorganisms pathogenic for flies of various species have 

 been described (i, 2). It was thought, therefore, that the 

 present phenomenon might also be due to the presence of some 

 pathogenic organism in the jars. With this idea in mind an 

 attempt was made to isolate such an organism from one of 

 the jars in which the flies had died very rapidly, and in which the 

 yellow growth was particularly thick. 



It has been observed by Pearl that flies might live in ves- 

 sels containing growth of Penicillium of the ordinary varieties 

 without any ill effects on the flies. Inasmuch as the mold in 

 question was believed to be one of these ordinary types, it was 

 thought that the obnoxious growth, if any were present, must be 

 connected with the yellow pigmentation, since this had not been 

 observed before and its appearance was connected with the death 



of the flies. 



11 i53 



