PHYSIOLOGICAL PROPERTIES OF THE GONADS. 303 



eral were allowed to live but fifteen days after go-nadectomy. The 

 majority of the cases compared indicate a tendency toward a 

 suprarenal hypertrophy in both sexes of the rabbit and guinea pig. 

 Hatai ('15) found that the suprarenal of the male rat increased 

 materially in weight after castration, whereas the female supra- 

 renal showed a decrease of from 5 per cent, to 25 per cent, com- 

 pared with normal females. In the guinea pig the relative weight 

 of castrated and normal male suprarenals in my experiments are 

 but little different. It appears, however, that there is a slight 

 reduction in the weight of these glands in the castrated animals. 

 In the spayed females the suprarenals were approximately 22 per 

 cent, lighter in weight than those of the normal females. 



The fundamental relationship between the sex glands and the 

 suprarenals may be actually different for different types of animal 

 forms, as is indicated by the discordant results reported. But it 

 is undeniable that more exact data are necessary before an approach 

 to the truth can be formulated. For the experimental data to be 

 of value comparisons must be made with animals of similar ages 

 and existing under similar living conditions. It is obvious, also, 

 that data based upon considerable numbers of operated cases are of 

 much greater weight than that obtained from a random comparison 

 of a few animals. 



VIII. GROWTH OF THE SPLEEN. 



While the spleen is not ordinarily considered an organ of in- 

 ternal secretion, it appeared desirable to include the weights of 

 this organ in the various animals, as all such data may prove of 

 value at a later time. 



Sexual Differences. Comparing the average weight of the nor- 

 mal male spleen (1.0305 grams) with that of the average of the 

 normal female spleen (1.0990 grams), one sees that the normal 

 female spleen is 6.6 per cent, heavier than that of the male; since 

 the average body weights are the same, we may conclude that there 

 is a slight sexual difference in the spleen favoring that of the 

 female. 



Castration. Comparing the average weight of the normal male 

 spleen (1.0305 grams) with the average weight of the castrated 

 male spleen (0.9037 gram), a slight difference is evident. The 



