442 WILLIAM H. F. ADDISON 



the debated question of the relation of the several cell-types seen 

 in the ventral glandular portion; i.e., as to whether they are 

 merely functional variations of one type, or really constitute 

 independent types of cells, each forming a different specialized 

 secretion. 



The present investigation was begun -as a study of the his- 

 tological details of the interesting observations of Hatai. These 

 were, in part, briefly, that there was a sex-difference in the 

 weights of the hypophyses of male and female albino rats, al- 

 ways in favor of the female (Hatai '13), and that after gonadec- 

 tomy, there was a decided increase in weight in the male hypo- 

 physis, but only a very slight increase in the female hypophysis 

 (Hatai, '15). 



It is proposed in the present paper to give a description of the 

 normal male hypophysis of the albino rat, and of the changes 

 consequent upon the removal of the sex-glands. Fichera ('05) 

 was apparently the first to study castration changes, using domes- 

 tic cattle, domestic fowl and European buffaloes, and his results 

 will be discussed later. No extended study has been made of 

 the albino rat in this respect, although a number of investigators 

 have worked upon other animals, with results somewhat at 

 variance. Reference will be made to these under the heading 

 "Discussion of Observations." 



In view of the discordant results, it has seemed advisable to 

 restrict the present phase of the work, to the one form, the albino 

 rat. 



MATERIAL AND METHODS 



Both young immature animals and adult animals were used. 

 The operations in the former were performed at about the age 

 of one month, and the experiments were* all done by litters, some 

 of the males of the litter being operated upon, and the remainder 

 kept as controls. The hypophysis material from the experi- 

 mented animals was taken at varying periods after operation, 

 the longest period being nine months. Always the hypophysis 

 from a control animal of the same litter was taken at the same 

 time. In the early part of the work, the weights of the hypo- 



