244 



ZALIA JENCKS 



a week's time intervened between return to normal and the following 

 bleeding, the regeneration rate was normal. Similar experiences have 

 been recorded by Geiling and Green for double hemorrhages. 



Blood regeneration in growing rats. To study the effect of loss of 

 blood on the growth of young animals bleedings were made on healthy 

 growing rats fed on the standard diet and brewery yeast as the adults 

 were fed, the hemorrhage procedure being the same as for the grown 

 rats. The time of total regeneration for these little rats was from 7 to 

 9 days (see table 2). After the hemorrhage they recovered quickly, 



TABLE i 

 Blood regeneration in adult rats after a single hemorrhage on the standard diet 



* The figures in the tables under the heading Red Blood Corpuscles give the 

 number of ery throcy tes before hemorrhage and the number at the end of recovery. 



continued to grow and increase their body weight in a normal manner. 

 Apparently the loss of one-third of their blood did not hinder growth 

 in any observable respect. Some young animals whose growth had 

 previously been delayed by lack of vitamin B in experiments by 

 Cajori (9) were also used, but these recovered in the same way as the 

 animals showing uninhibited growth. 



Diet and dietary factors. In order to make these experiments as 

 accurate as possible and to eliminate some of the variables occurring in 

 other work on blood regeneration, the standard diet, with the addition 

 of dried brewery yeast, was used. Diets of each component of this 



