EFFECT OF CASTRATION ON THE WHITE RAT 303 



final body weight of 151 grams. (The hypophysis was not exam- 

 ined in two rats.) Barnabo concludes that the weight of the 

 hypophysis is not altered as the result of operation. No data 

 given regarding the control rats, and it is merely stated "Per 

 altro controllo mi sono poi servito di animali normali." 



It is true that Barnabo's experiment (except series 3) is differ- 

 ent from that of my own, not only in the method of operation, 

 but by reason of the fact that Barnabo operated on the sexually 

 mature animals, while the rats examined by me were operated 

 on while still very young (about twenty-five to thirty days of 

 age). Thus the two experiments may not be strictly comparable, 

 nevertheless according to our formula (Hatai '13) which is based 

 on large numbers of normal rats, the weight of the hypophysis 

 given by Barnabo is almost 150 per cent heavier than it ought 

 to be for the body weight given. It seems highly probable that ' 

 Barnabo did not realize the existence of the striking sex difference 

 in the weight of the hypophysis, and thus the operated rats may 

 have been compared with the normal female albino rats, in which 

 case but slight differences might appear as the weight of the 

 hypophysis in the female is more than twice that in the male 

 (Hatai '13). 



There are several investigators who also have noted in other 

 animals an enlargement of the hypophysis as the result of castra- 

 tion. For instance Fichera ('05) noted it in guinea pigs, rabbits 

 and several other animals, and Kon ('08) in man. The clinical 

 observations on the subject are very numerous, but these will not 

 be discussed at the present moment. 



On the other hand, Marrassini and Luciani ('11) also using 

 guinea pigs, rabbits and some other animals, recently obtained 

 contrary results, that is they found that castration does not 

 produce any noticeable enlargement of the hypophysis in the 

 forms studied by them. Marrassini and Luciani's experiments 

 were carried on in a very satisfactory manner, since their operated 

 animals were contrasted with well chosen controls, and in addition 

 the number of animals used was much greater than in most of 

 the other researches. The probable cause of the conflict in these 

 results will be discussed later. 



