298 CARL RICHARD MOORE. 



unravel the existing relations between the sex glands and the 

 hypophysis. Hatai ('13) has shown that the hypophysis of the 

 female albino rat is more than twice the weight of that of the 

 male, and that in the Norway rat weight difference is also con- 

 stant, but of less degree than in the albino variety. As noted 

 above, the female guinea-pig hypophysis was heavier than the male 

 gland, though the difference in this case is but 7 per cent. Too 

 few determinations have been made, however, to warrant the con- 

 clusion that the same result, in general, would hold for other 

 animals. 



There is a great amount of controversial evidence on the effects 

 of gonadectomy on the hypophysis, not only among the different 

 groups of animals investigated, but also for the same group in- 

 vestigated by different workers. Fischera ('05) maintained that 

 the hypophysis increased very materially in weight when gona- 

 dectomy was performed on the common fowl, cattle, rabbit, guinea 

 pig, and buffalo. Marrassini and Luciani ('n), however, denied 

 an increase in the hypophysis under these conditions for practically 

 the same group of animals utilized by Fischera. And since the 

 publications of the latter an increase in the hypophysis following 

 gonadectomy has been reported for the female dog and rabbit 

 (Parhorn and Goldstein, '05), male dog and rabbit (Cimorini, 

 '08), male and female rat (Hatai, '13); but an increase of the 

 hypophysis has been denied for the male guinea pig (Pirsche, '02), 

 the male of the common fowl, cattle, dog, rabbit, guinea pig, sheep, 

 and the female guinea pig (Marrassini and Luciani, J n). These 

 very different results are undoubtedly due to inadequate controls. 

 It is very difficult to judge, in most instances, if the conclusions 

 drawn are warranted by the materials considered; even if they 

 are, the majority of observations have been made upon an inade- 

 quate number of animals, many times even upon animals of a 

 different stock. It appears that the observations of Hatai stand 

 almost alone in respect to the materials used, for in this investiga- 

 tion the growth relations are sufficiently understood and conducted 

 upon a sufficient number of animals to warrant an adequate com- 

 parison. 



Without attempting to discuss the ideas of the various writers, 

 advanced as explanations of their own particular results, I will 



