VITAMIN B (B^) 



101 



in a less rapid loss of weight and a prolongation of the survival period ; 

 but as the allov^ance is increased, growth at increasing rate is obtained. 



Different workers have made quantitative comparisons at different 

 levels of vitamin intake and maintenance or gain of weight. To facili- 

 tate comprehensive comparisons it may therefore be desirable to feed 

 at several different levels. 



The average results of feeding the same vitamin-B-containing food 

 at nine different levels is shown, along with the results of the ("nega- 

 tive") controls in Fig. 5 from the work of Chase (1928). 



60 



so 



40\-' 



to 30 

 5 20 



% 



-10 

 "20 

 -30 



10 20 30 40 SO 60 

 T/ME JN DAYS 



Fig. 5. — Average gain curves of rats on vitamin B-free diet (No. 513) plus 

 daily supplements of ground whole wheat of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8, and 1.0 

 grams. Negative controls (marked 0.0) received basal diet only. 



* P = Point where, on the average, chronic symptoms of polyneuritis appeared. 



Lines broken from the points at which some individuals died. 



(Courtesy of Dr. E. L. Chase.) 



In all cases in which the results are to be compared directly, the 

 feeding experiments are conducted in parallel between groups matched 

 as to sex and weight after depletion, and containing representative ani- 

 mals of the same litters. The response of the rats has been observed 

 to vary with graded increments of vitamin-B-containing food material, 

 from death with or without severe polyneuritis in from 20 to 30 days ; 

 through maintenance of body weight for 8 weeks with moderate poly- 

 neuritis during the latter half of that time ; and through growth with 

 apparent protection from polyneuritis ; up to a normal rate of growth 

 throughout. 



