SHORTER ARTICLES AXI) 1)IS(M'SSI()X 



SOLID MEDIA FOR RHAi;i.\(i )S< >1>II1LA 

 Baumberger and Glaser (1) rccnitly (loscriluMl a iiK'thotl of 

 raisino; the banana fly on transparent, solid media, thus enahling 

 the investigator to observe more accurately the rate of growth 

 and metamorphosis and the larval habits of this insect. The 

 medium was made as follows: 



Five or six bananas were mashed up in 500 c.e. of water. This was 

 allowed to infuse on ice over nij^ht. after which the liquid was passed 

 through cheese cloth. Powdered agar-atrar was then added in tlie pro- 

 heated until the agar had dissolved. Tlic li(inid was then iiltcred 

 through a thin layer of absorbent cmtnn into tcsl Inhcs. The tubes 



As pointed out in the above article, one of iis ( l' i liad ob^rrvcd 

 that the bacterial growths which always develop on tins nuMlium 

 "do not seem to harm the larvae" and the uiolil which Nmurtinics 

 appears "is usually destroyed by the larvae just as soon as they 

 hatch." This question was further investigated and it was 

 found (2) that the prinicpal food of Drosophila is yeast and the 

 flies can not develop on banana which is kept free from micro- 

 organisms.i Delcourt and Guyenot bad lu-eviously (un- 

 known to the author) published siniiliir corn-lusions iiiid T.oeb 

 and Northrop (4) bad confirmed tiieiii shortly before tlic aurhor's 

 report (2) was sent to press. 



It is therefore very well known that the food of Drosophila is 

 yeast and the prime necessitv of any meduim for rearing this fly 

 must be either abundant food for yeasts to grow upon or the 

 presence of large numbers of yeast cells. If a medium is made 

 of sterile compressed yeast and agar-agar- it serves as a perfect 

 food for flies which have been freed from niu-foot iriiiiiMns : how- 

 ever, if living yeasts develop young larvje are usiuiliy kill.Ml. As 



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