A NUTRITIONAL STUDY OF INSECTS 



21 



symptoms of protein deficiency. This deficiency is quantitative 

 rather than qualitative, because more normal growth of the lar- 

 vae is permitted when the fruit is concentrated. 



As these symptoms of malnutrition are not shown in larvae 

 reared on yeast, we would expect to find a high protein content of 

 adequate components in this food. This assumption is correct, 

 for Atwater and Bryant ('02) have found by analysis that the 

 percentage protein content of yeast is 11 per cent. This is higher 

 than the percentage occurring in any fruit or in Agaricus campes- 

 tris, and Meisenheimer ('05) has shown that most monoamino- 

 acids occur in yeast protein. 



^— Pupa/ioff. 



^ — ^ — T 



^ge //> ^<yy-^ ■ 



"I ^ 



Fig. 6 Larval growth on mushroom. 3. 4, mushroom; 1, normal growth on 4 

 per cent yeast; 2, growth of larvae of mushroom-fed adults on 4 per cent yeast. 



Is the rapid growth of larvae on yeast due to this high protein 

 content or to other substances present in the yeast ceU, such 

 as glycogen, fat, gums, hemicelluloses, etc.? By extracting the 

 yeast nucleoprotein and making media with known sugars and 

 salts, this problem was solved. The method employed to extract 

 the yeast nucleoprotein and to make the media is described in a 

 foot-note below. 11 



^1 The pure yeast nucleoprotein was obtained in the usual manner (Hawk, '16), 

 as follows: the cells in 4 pounds of baker's yeast (Fleishmann's bottom bread 



