Drosophilidae 445 



TECHNIQUE FOR SPECIES OTHER THAN D. MELANOGASTER 



The foregoing account is intended to apply to Drosophila melanogas- 

 ter, the most used species. With one or two modifications, however, the 

 same technique may be used successfully for many other species of the 

 genus. 



Most of these species are more sensitive to high temperature; 25 

 is satisfactory for D. simulans, D. funebris, D. virilis, D. busckii, or D. 

 repleta. For the members of the D. affinis or D. obscura groups it is 

 best to use 24° or less. For other forms experiment will show what is 

 optimum. 



The other modification often necessary arises from the fact that many 

 of the other species require to be aged longer before they are ready 

 to lay. In the case of D. simulans one day in the vial is adequate, but 

 all the other forms that I have bred extensively require more than this. 

 For D. pseudobscura three days, or better four, is usual; for D. affinis or 

 D. repleta a week is desirable. D. funebris and D. virilis need nearly as 

 long a period. In these cases, if the females are put into the culture bot- 

 tle too soon they usually fail to lay any eggs, though they may survive 

 and may produce offspring if transferred to fresh medium later. My 

 experience has been, however, that females of these species are much 

 more likely to breed if they have been given fresh food about 24 hours 

 before they are transferred to the culture bottle. 



In dealing with the more difficult species it is especially necessary to 

 avoid rough treatment, as this usually interferes with egg laying even 

 more markedly than it does in D. melanogaster. 



Reference 

 For the culture of Drosophila see also p. 305. 



Bibliography 



Baumberger, J. P. 1919. A nutritional study of insects with special reference to 



microorganisms and their substrata. /. Exper. Zool. 28:1. 

 Bridges, C. B. 1921. Gametic and observed ratios in Drosophila. Amer. Nat. 55:52. 



■ — 1932. Apparatus and methods for Drosophila culture. Ibid. 66:250. 



Bridges, C. B., and Darby, H. H. 1933. Culture media for Drosophila and the 



pH of media. Ibid. 57:437. 

 Delcourt, A., and Guyenot, E. 1911. Genetique et milieu. Necessite de la 



determination des conditions ; sa possibility chez les Drosophiles. Bull. Sci. France 



Belg. 45:249. 

 Gershenson, S. 1928. A new sex-ratio abnormality in Drosophila obscura. 



Genetics 13:48. 

 Guyenot, E. 1917. Recherches sur la vie aseptique et le developpement d'un 



organisme en fonction du milieu. Thesis, Paris, 330 pp. 

 Komai, T. 1927. The culture medium for Drosophila. Science 65:42. 

 Northrop, J. H. 1917. The role of yeast in the nutrition of an insect (Drosophila). 



J. Biol. Chem. 32:123. 



