250 



ZALIA JENCKS 



no yeast, i.e., no vitamin B, was given to them; they were bled accord- 

 ing to the regular procedure and their recovery was apparently normal. 

 They ate less and less as time went on, as has been the case for all 

 animals with lack of vitamin B (12), and they lost in weight. The 

 return to normal blood values came in from 12 to 13 days; in three of 

 the four cases hemoglobin values were low. This could not be due to 

 lack of iron, for some iron was eaten in the salt mixture, although more 

 iron would have been consumed had yeast also been added to the diet 

 (table 10). 



Yeast only. Because of these results with protein-free food and with 

 other diets without yeast, a series of hemorrhages was made on rats 

 which were fed nothing but yeast during the period of recovery. AC- 

 TABLE 10 



Blood regneration in adult rats after a single hemorrhage; on the standard diet, 



without yeast 



cordingly four animals were selected which had responded in a normal 

 manner to regeneration after experimental anemia several weeks pre- 

 vious to this time and each was again subjected to a hemorrhage. 

 These rats were then fed 0.5 gram dried brewery yeast daily. They 

 ate the yeast with great avidity as soon as it was offered. This 

 amounted to practical starvation, and although they lost body weight 

 the animals all regenerated their blood in from 6 to 8 days (table 11). 

 In each case the hemoglobin values were equal to or exceeded the origi- 

 nal. This group of animals regenerated their blood in less time than 

 the group without food. 



As a check for these results with yeast alone a group was given 0.5 

 gram protein (casein) daily to see if the small quantity of yeast protein 

 was the stimulant to forming new blood or whether it was in truth the 



