314 



THE BIOCHEMISTRY OF B VITAMINS 



Because of the nicety of quantitative response obtainable, Sarma and 

 co-workers have employed Corcyra as an assay animal for thiamine, 

 riboflavin, and pyridoxine, and obtained results which agree well with 

 those obtained by other methods. Strain differences, however, are suf- 

 ficiently great that "pure" strains would be desirable for routine insect 

 assay work. 30 - 31 - 36 



Figure 4. Growth of Corcyra Cephnlonicn St. larvae with various amounts of 

 biotin concentrate added to an egg-white diet. Ten larvae per test group. 



Of even greater interest, however, is the work done by this group on 

 vitamin metabolism in insects. 37 In a manner entirely analogous to that 

 of higher animals, thiamine-deficient Corcyra larvae show fatty tissue 

 and nerve degeneration, and the pyruvic acid content of the deficient 

 larvae increases to eight times that of the normal animals (p. 403), and 

 decreases again on a high thiamine diet. Again, vitamin B 6 deficient larvae 

 on high tryptophan diets excrete a yellow pigment which disappears on 

 supplementation of the diet with pyridoxine, in a manner remarkably 

 suggestive of the abnormal xanthurenic acid (yellow) excretion in vita- 

 min B 6 deficient mammals (p. 428). As in mammals, tryptophan alone 



