PHYSIOLOGY, CHEMISTRY AND PATHOLOGY 25 



operated upon, varied in age from two days to six or seven weeks, and 

 usually the experimental and control animals were members of the same 

 litter. 



On the whole, the animals did very well, considering that they were 

 operated upon at so early an age, and if tided over the first forty-eight 

 hours they usually lived until sacrificed, although a few of both experi- 

 mental and control animals died after the course of several weeks, due to 

 intercurrent causes. In all, 144 guinea pigs were operated upon, and of 

 these an attempt was made in eighty-two to extirpate the gland, while in 

 the remaining sixty-two a control trepanation was performed. The larger 

 number of experimental animals is due to the fact that the operation upon 

 them being more severe, there were more immediate casualties, necessitat- 

 ing a greater number of subjects for operation. Of the eighty-two experi- 

 mental animals, forty-eight lived to maturity or until sacrificed, while of 

 the sixty-two controls, forty-two lived an equal length of time as the cor- 

 responding experimental animals. 



In nearly every instance, postoperative death was due to hemorrhage 

 from the large vein of Galen. The mortality is necessarily high. 



Results in Males. As to results in the males, taken as a whole, very 

 little difference was noted in the body weights of the experimental and 

 control animals. The average weight of the former at the time of opera- 

 tion was slightly less than that of the controls, and when sacrificed from 

 the fourth to the seventh week after operation, there was a slight gain in 

 favor of the experimental animals, but both values are possibly within 

 the normal limits of variation. 



In regard to the growth of the genital organs, a much more notice- 

 able increase took place in favor of the experimental animals. The 

 total weight of the testes of these was 12,815 mg. against 9,950 mg. total 

 for the controls. 



It was noted, also, that the experimental guinea pigs showed a marked 

 increase in the size of the seminal vesicles over those of the controls. No 

 mention appears to have been made by other investigators concerning 

 these organs. The experimental animals showed a total weight of the 

 seminal vesicles of 11,450 mg. against the controls' 7,000 mg., or an 

 average of 763.3 mg. for the former against 466.6 mg. for the latter. 



Microscopically, the differences in the testes of the experimental and 

 control animals were perhaps not so marked as might be expected from a 

 comparison of their gross size and weight. Nevertheless, in this respect 

 also, there were changes which indicate a hastened development of the 

 organs under consideration. The most marked differences occurred in 

 animals which were sacrificed between the ages of nine and eleven weeks. 

 If sacrificed before this age, practically no microscopic differences could 

 be detected, while later than eleven weeks the difference again became very 

 slight owing to the proximity of normal maturity. 



