ENDOCRINE FUNCTION OF THE THYMUS GLAND 



321 



The slight fluctuations of body weight in our charts depend 

 very much upon the amount of stomach contents of the rats'. 

 Though the weighing was done mostly at a definite time in tjie 

 morning before the regular feeding of the rats, circumstanceB 

 sometimes obliged us to weigh our rats at other times. In any 



BODY WEIGHT GRAMS 



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I I I I M 



Chart 1 The average growth curve in body weight on age. series II. The 

 number of test rats, 4; the number of control rats, 5. The inverted black-dot 

 arrows (D denote the injection of the antithymus serum into the test rats. 

 The ring arrows (J) indicate when each control rat was taken for examination. 



case, all the individuals in a litter were weighed at the same time. 

 A special analysis of the weight of the thymus gland of all rats is 

 worth recording here (tables 3, A, and 3, B). The calculate.d 

 values are based on table 72 in The Rat (Donaldson, '15). 



The data on the weight of the other organs do not show any 

 definite difference between the test and control animals, and 

 therefore are omitted entirely. 



THE JODKNAL OF EXPERIMENTAL ZOOLOQY, VOL. 29, NO. 2 



