338 THE PHYSIOLOGY OF REPRODUCTION 



secondary sexual characters of animals are usually arranged symmetri- 

 cally. The effect produced by one-sided castration is general rather 

 than local, and the operation has little or no influence in destroying 

 the symmetry of the sexual characteristics (c/., however, Fowler's 

 statement about fallow deer, which appears to be exceptional). It is 

 probable, therefore, that Pfliiger is correct in supposing that the 

 internal secretion of the testis acts as a direct stimulus upon the cells 

 of the frog's arm and so induces the development of the sexual pad 

 and the hypertrophy of the muscle. 1 



- Meisenheimer 2 has confirmed the results of Nussbaum's experiments 

 on castration and testicular transplantation in the frog, but Smith 

 and Schuster, 3 who have repeated the experiments, while admitting 

 that the castration effect occurs, were sceptical about the efficiency of 

 the grafts, their own transplantation experiments being negative. 

 The latter authors further criticise Nussbauin and Meisenheimer's 

 conclusions, stating that "the effect of castration, except actually 

 during the breeding season, is to make the papillre on the thumb-pads 

 remain essentially in the condition they were at the time of castration." 

 Meisenheimer's claim to have induced hypertrophy as a result of 

 ovarian transplantation they regard as quite unproved. 



According to Kammerer 4 the pad can develop in the breeding 

 season in Alytes in individuals previously castrated. 



There is some evidence to show that, after one-sided castration, 

 the remaining testis is capable of undergoing a compensating 

 hypertrophy, 5 and according to Ancel and Bouin 6 and others there 

 is a compensatory enlargement of the interstitial gland. Lipschiitz 7 

 has thrown some doubt on this conclusion, pointing out that a very 

 small fragment of testicular tissue suffices for the development and 

 maintenance of the sexual characteristics, as shown both by himself 



1 See also Nussbaum, "Hoden und Brunstorgane, etc.," Pflitger's Arch., 

 vol. cxxvi., 1909. For further references to the literature of testicular trans- 

 plantation, see Boruttau, " Innere Sekretion," in Nagel's Handbuch der Physiologie 

 des Menschen, Braunschweig, 1906 ; and Harms, Experimentelle Untersuchungen 

 liber die innere Sekretion der Keimdrusen, Jena, 1914. 



2 Meisenheimer, "Ueber die Wirkung von Hoden- und Ovarial Substanz 

 auf die Sekundaren Geschlechtsmerkmale des Frosches," Zool. Anz., vol. xxxviii., 

 1911. 



3 Smith and Schuster, " Studies in the Experimental Analysis of Sex," 

 Part 8, Quar. Jour. Micr. Science, vol. Ivii., 1912. 



4 Kammerer, "Vererbung Erzwungener Formveranderungen, etc.," Arch, 

 f. Entwick.-Mechanik, vol. xliv., 1919. 



6 Ribbert, "Beitrage zur kompensatorischen Hypertrophie, etc.," Arch. f. 

 Entwick.-Mechanik, vol. i., 1894. 



6 Bouin and Ancel, " Recherches sur le Role de la Glande Interstitielle, etc.," 

 C. R. de VAcad. 8ci., vol. cxxxvii., 1903; "La Glande Inst., etc.," C. R. de 

 I'Acad. 8ci., vol. cxxxviii., 1904 ; "De la Glande, etc.," Jour, de Phys. et Path., 

 vol. vi., 1904. 



7 Lipschiitz, Ottow, Wagner, and Bormann, "On the Hypertrophy of the 

 Interstitial Cells in the Testicle of the Guinea-pig, etc.," Proc. Roy. Soc., B., 

 vol. xciii., 1922. 



