STUDIES IN THE REGENERATION OF BLOOD 



249 



this protein-free food daily, hemorrhages were made and the process 

 of blood regeneration watched by the methods used before. These rats 

 replenished their blood supply in from 9 to 12 days (table 9), slightly 

 more time being required in this series than in the case of the diets of 

 fat only, but in one case less than with carbohydrate only. Yeast was 

 fed with this protein-free food to the extent of 0.1 gram per day but 

 the exceedingly small amount of protein therein evidently had little 



TABLE 8 



Blood regeneration in adult rats after a single hemorrhage; on a carbohydrate diet 

 2 grams cornstarch per day 



TABLE 9 



Blood regeneration in adult rats after a single hemorrhage; on a protein-free diet 



5 grams per day 



or no effect on the speed of blood-cell formation. In all cases it was 

 impossible to keep the animals eating this ration without the addition 

 of the dietary essential, vitamin B. This led to work on diets without 

 added yeast, with yeast as a sole source of nourishment, and with other 

 vitamin-containing products, such as tomato juice and orange juice 

 alone. 



Standard diet without yeast. Four rats were supplied with an unre- 

 stricted quantity of standard diet and an abundance of fresh water, but 



