Relation between the Thymus and the Generative Organs. 69 



which these conclusions are based are dealt with statistically in an appendix 

 to this paper by Mr. G-. Udny Yule. 



Noel Paton's conclusions have been challenged by Soli, who worked upon 

 guinea-pigs and upon fowls. The guinea-pigs, except in the case of two. 

 pairs, were killed when weighing considerably over 300 grm., so that the 

 results have no bearing upon Paton's assertion that in guinea-pigs below 

 that weight thymusless animals tend to have larger testes than normal 

 individuals. In the two pairs killed below 300 grm. the testes of the 

 operated guinea-pigs were slightly lighter than those of the control animals. 

 In the experiments upon fowls Soli found that in two cases the thymusless 

 birds had heavier testes than the controls, but in 11 cases the testes of the 

 operated individuals were lighter than those of the unoperated. Paton,- 

 however, points out that in certain of these the rate of growth was below 

 the normal, and that the small size of the testes might have been due to 

 inferior nutrition. Soli found that castration produced hypertrophy of the 

 thymus or arrested atrophy in that organ. In the unoperated birds the 

 average weight of the thymus was - 6 grm. to each kilogramme of body 

 weight, whereas in the capons its weight was 1*16 grm. to each kilogramme 

 of body weight. 



Gellin, Klose and Vogt, Marrassini, and Squadrini have also found that 

 castration tends to enlargement of the thymus, or arrests the normal 

 involution of the gland. 



As a result of a further series of experiments, Paton has concluded that 

 the thymus and the testis do not act antagonistically to one another, but 

 that each organ has a stimulating influence upon growth, the one organ 

 compensating for the removal of the other by undergoing hypertrophy. 

 Paton found that castration alone without thymectomy had no effect upon 

 the growth of young guinea-pigs, neither had thymectomy alone any 

 influence upon the rate of growth. On the other hand, castration and 

 thymectomy performed simultaneously in very young guinea-pigs was found 

 to check growth. Considered in the light of our experiments to be 

 described below we are of opinion that this effect may have been consequent 

 upon the double operation, which very possibly lowered the resistance of 

 the animals towards disease. Paton describes further experiments showing 

 that in six castrated males and four castrated females the average weight of 

 the thymus was greater than in control animals. 



Basch, and also Klose and Vogt, describe extirpation of the thymus in 

 dogs as producing a softening of the bones or retarding the growth of the 

 bony tissues, besides causing other pathological phenomena. Similar changes 

 resulting from thymectomy are described by Matti. Soli also has confirmed 



