40 



THE SEX-COMPLEX 



Comparison 



secretion of 



the thyroid 



and the 

 pituitary. 



Eeasonof 



oTtoeYhyr 

 in rodents, 



a cycle of events to be demonstrated in the hypophysis 

 according to the needs of the moment. It is probable, 

 then, that the basophil colloid found in the rabbit's 

 thyroid after oophorectomy represents a storage secre- 

 tion ^ wnicll j s f orme d to meet the altered conditions of 

 metabolism, but which is not of a great degree of 

 physiological activity in this order of mammals. 



As we have previously suggested 1 , the inactive 

 thyroid which is found in rodents is probably related to 

 the very remarkable development of the interstitial 

 cells in the ovaries of these animals. In consequence 

 of this a marked change is produced in the thyroid of 

 rodents by oophorectomy, and not to the same degree 

 in other mammals, such as the carnivora. Moreover, 

 thyroidectomy is comparatively harmless in rodents. 

 Some have argued, however, that the distance of the 

 parathyroids from the thyroid in herbivora prevents 

 their removal at the operation, and that the effects 

 produced in carnivora by thyroidectomy are due to the 

 removal of the parathyroids (see p. 50). This is not 

 necessarily so, for I have been able to keep alive a cat 

 with myxoedema for over a year. 



McCarrison 2 and others, however, have pointed out 

 that the thyroids of animals of the same species kept 

 under similar conditions vary enormously. 



EFFECTS OF OOPHORECTOMY ON THE THYMUS 



Hypertrophy Calzolari 3 . first stated that castration produces 



afte/o^phor- hypertrophy of the thymus. His experiments were 



ectomy. carried out on rabbits. It has, also, been noted by 



Marrassini 4 and by Gellin 5 that castration after genital 



activity has been established gives rise to enlargement 



of the thymus. No work has been done in regard to 



Bell, W. Blair, and P. Hick, Brit. Med. Journ., 1909, vol. i, p. 655. 

 McCarrison, R., Lancet, 1914, vol. i, p. 931. 

 Calzolari, A., Archiv. Ital. de BioL, 1898, vol. xxx, p. 71. 

 Marrassini, A., Archiv. Ital. de BioL, 1910, vol. liii, p. 419. 

 Gellin, (X, Zeitsch. f. Exper. Palhol. u. Therap., 1910, vol. viii, 

 p. 1, 



