Relation between the Thymus and the Generative Organs. 71 



pigs were used. The experiment started on December 20, 1912. On 

 February 7 the testes from six guinea-pigs were removed. On March 4 the 

 thymuses of the entire set were extirpated. The animals were killed on 

 May 9. The number of animals taken was too few to establish any possible 

 growth effects due to removal of the thymuses and testes. The animals 

 retaining the, testes grew less in the later stages of the experiment, this 

 possibly being due to the castration effect on growth observable in all 

 castrated adult animals. With regard to the effect on the thymus, small 

 though the number of animals is, the evidence is quite clear. Moreover, the 

 fact that the animals castrated had all attained puberty before castration 

 took place shows that the arrested atrophy and subsequent hypertrophy of 

 the thymus cannot be explained by Paton's theory. 







Days after first weighing. 

















Weight 



Animal No. 











of thymus. 





0. 



49. 



74. 



140. 









Control Animals. 









grm. 



grm. 



grm. 



grm. 



grm. 



1 



237 



355 



475 



580 



0-276 



2 



192 



335 



354 





0-342 



3 



215 



358 



442 



497 



0-370 



4 



214 



342 



452 



617 



0-337 



5 



202 



357 



377 



588 



400 



Average — 









570 





4 animals 







436 





5 „ 



212 



349 



420 





0-345 







Operated Animals. 







1 



212 



355 



402 



615 



-430 



2 



240 



400 



470 



682 



0-395 



3 



184 



345 



375 



567 



-470 



4 



187 



360 



380 



610 



0-564 



5 



225 



375 



447 



674 



0-680 





209 



367 



415 



629 



-508 



Experiment 2 (figs. 1, 2, and 3) : Effect of Removal of the Testes on the 

 Weight of the Thymus, of Removal of the Thymus on the Weight of the Testes, 

 and upon the Growth of the Animal. — This set contained 10 normal animals, 

 7 castrated, and 6 thymectomised. The animals were operated upon on 

 February 24-27, and first collectively weighed on March 4. On May 9 the 

 experiment terminated. 



