24 



J. PERCY BAUMBERGER 



TABLE 7 



X No eggs laid. 

 d indicates death. 

 * Media dried. 



Hence the objection that there is no exact mathematical corre- 

 lation between the rates of growth and the protein concentration 

 is not irrefutable evidence against the view that primarily such 

 a relationship exists. For example, some farm animals will lose 

 weight on a soy-bean diet of high protein value, but of a taste 

 they do not like. 



Since Drosophila grows noiTnally, pupates in large numbers, 

 and develops into fertile adults of good size, it appears that a 

 medium of yeast nucleoprotein, sugars, and inorganic salts is a 

 complete food for this insect. It has already been proved by 

 experiment (p. 13) that larvae do not grow on sugars and inor- 

 ganic salts alone, so that the nucleoprotein is the substance which, 

 if added, makes the medium equivalent to yeast cells as food for 



