VITAMINS 243 



Glaser (1923) has shown that the house-fly in captivity lives 

 only a few days and lays no eggs on a diet of proteins or products 

 of protein hydrolysis, or of raw starch. When fed on sucrose, 

 longevity is increased but no eggs are laid, while on a diet either 

 of sucrose and bouillon, sucrose and blood serum, glucose and 

 bouillon or of glucose and blood serum, longevity and oviposition 

 reach their maximum. Longevity is also high and eggs are laid 

 on a diet of soluble starch and bouillon or of hydrated starch and 

 bouillon. It appears, therefore, from his experiments that sugar 

 or assimilable starch, together with a solution of proteins or 

 products of protein hydrolysis, like bouillon or blood serum, are 

 necessary for oviposition. 



Vitamins. Further and more detailed analyses of the nutritional 

 requirements of certain insects lend support to the conclusion that 

 they, similarly to the higher animals, exhibit certain vitamin 

 requirements in order to undergo normal growth. In some cases 

 complete growth is unobtainable unless certain accessory food- 

 substances are included in the diet, while in other cases such 

 requirements do not appear to exist. The latter conclusion is 

 always confronted with the difficulty that unless the insect be 

 reared aseptically from the egg, the possibility that growth- 

 promoting substances are contained in micro-organisms present 

 in the gut, or other organs of the insect, cannot be excluded. The 

 difficulties to be faced in rearing many species of insects under 

 absolutely aseptic conditions can scarcely be overcome, since in a 

 number of cases micro-organisms are known to be present in the 

 egg and are transmitted from generation to generation. 



A considerable amount of research has been carried out with 

 respect to the influence of vitamins on the growth of Drosophila 

 and other insects, and short reviews of the subject are given by 

 Richardson (1926) and by Uvarov.(1928). With respect to the 

 species Drosophila melanogaster, the earlier work of Loeb and 

 Northrup, and of Northrup, showed that the larvae of this insect 

 require a growth-promoting substance present in yeast in order 

 to complete their development. Guyenot confirmed their findings, 

 and concluded that the substance present in yeast, which is 

 indispensable for growth, resembles in certain respects the water- 



