38o THE PHYSIOLOGY OF REPRODUCTION 



organ, there was an increase in the growth of the testis. On the 

 other hand, Soli ^ states that extirpation of the thymus, carried out in 

 young rabbits, guinea-pigs, and fowls, caused inhibition of testicular 

 development, and sometimes even complete arrest of growth by 

 that organ. 



Lucien and Parisot ^ also found some arrest in the growth of the- 

 testes after thymectomy in the rabbit. Klose and Vogt,^ who worked 

 on dogs, reported hyperplasia of the testes followed by atrophic 

 changes. They also describe thymectomy as producing a softening of 

 the bones or a retardation of the growth of the bony tissues, besides- 

 other pathological phenomena. Similar changes are recorded by 

 Matti,* who was, however, unable to find any relation between 

 thymectomy and the time of spermatogenesis. Pappenheimer,^ work- 

 ing upon rats, obtained no evidence of thymectomy having any effect 

 upon spermatogenesis or the weight of the testes. 



As a result of a further series of experiments Paton ^ concluded 

 that the thymus and testes do not act antagonistically to one another, 

 but that each organ has a stimulating effect upon growth, the one organ 

 compensating for the removal of the other by undergoing hyper- 

 trophy, whereas neither castration nor thymectomy alone had any 

 influence upon growth. The double operation upon young guinea- 

 pigs checked growth. 



Mr. Hainan and the present writer,' in a series of experiments 

 upon guinea-pigs, while confirming the castration effect upon the 

 thymus, failed to obtain evidence of the thymectomy effect either 

 upon growth or upon the testes ; we found further that simultaneous 

 removal of the testes and thymus did not inflaence growth. Our 

 results, as well as those of Paton, were analysed by Udny Yule, who 

 concluded that Paton's thymectomy results may have been due to 

 chance variation. 



According to Hewer ^ it is possible to induce a hyperthymic 



' Soli, "Contribution a la Oonnaissance de la Formation du Thymus chez 

 le Poulet et chez quelques Mammifferes," Arch. Ital. de Biol., vol. Ixii., 1909. 



^ Lucien and Parisot, "Variation ponderale consecutive a la Thymectomie 

 chez le Lapin," C. R. de la Soc. de Biol., vol. Ixv., 1918. 



' Klose and Vogt, " Klinik und Biologie der Thymusdrtise," Beitr. z. hi. Chir., 

 vol. xcii., 1910. 



* Matti, " Untersuchung ueber die Wirkung experimentellen Ausshaltung 

 d. Thymusdruse," Grenzgeb. d. Med. u. Chir., vol. xxiv., 1912. 



^ Pappenheimer, "The Thymus Gland, etc., and the Female Genital Tract," 

 Sura., Obstet. and Gyn., vol. xxv., 1916. This paper contains many references. 



" Paton, " The Thymus and Sexual Organs," Jour, of Physiol., vol. xlii., 

 1911. 



' Hainan and Marshall, "On the Relation between the Thymus and 

 Generative Organs, etc.," with a Note by Udny Yule, Proc. Roy. Soc, B.> 

 vol. Ixxxviii., 1914. 



^ Hewer, "The Effect of Thymus Feeding, etc.," Jow. of Physiol., vol. xlvii., 

 1914 ; " The Direct and Indirect Effect of X-Eays on the Thymus Gland and 

 Reproductive Organs," Jour, of Physiol., vol. 1., 1916. 



