STUDIES IN THE EXPERIMENTAL ANALYSIS OF SEX. 469 
(4) Ovariotomy, with or without subsequent implantation 
of testes or injection of testis-extract, has no effect in 
making the thumb of the female assume any male characters. 
(5) Castration in the male, except during the breeding 
season, does not have any marked effect in reducing the 
papillation of the thumb, the papillae in a castrated frog 
remaining for a long period (at any rate, four to five months, 
and probably much longer) in the same condition as they 
were at castration. Castration during the breeding season is 
followed by a rapid throwing-off of the outer papillated 
layers of the thumb-pads. 
(6) Implantation of testis-pieces or of whole testes, or the 
injection of testis-extract, has an entirely negative effect on 
the thumb of castrated frogs, and does not cause any appre- 
ciable increase of the papillse. 
(7) The positive results claimed by Nussbaum and 
Meisenheimer, as following the treatment of castrated frogs 
by the above and similar means, are criticised and shown to 
be altogether unproved. There is, therefore, no evidence 
that the testes of the frog contain an internal secretion which, 
on being injected into a castrated frog, calls forth the increase 
of the papillge on the thumb. 
List of Literature. 
1. Nussbauin, M. — ‘Archiv f. Mikroscop. Anat.,’ Bel. xviii, 1880. 
2. Ploetz. — ‘Archiv f. Anat. und Physiol.,' Physiol. Abth., 1890, 
Supplement Band. 
3. Borattau. — ‘ Nagel’s Handbuch der Physiologic des Mensclien,’ 1906. 
4. Ribbert. — ‘Archiv f. Entw. Mecli.,’ vii, p. 688, 1898. 
5. Foa, C. — ‘Archives Italiennes de Biol./ vol. xxxv, pp. 337 and 364, 
1901. 
6. Herlitzka, A. — ‘Archiv f. Entw. Mecli.,’ Bd. ix, p. 140, 1899, and 
‘Archives Italiennes de Biol.,’ vol. xxxii, p. 274. 
7. Foges, A. — ‘ Pfliiger’s Archiv. of Physiologie,’ Bd. xciii, p. 39, 1902. 
8. Shattock and Seligmann. — ‘ Proc. Roy. Soc.,’ vol. lxxiii, 1904. 
9. Marshall and Joly. — ‘ Trans. Roy. Soc. Edin.,’ vol. xlv, 1907, and 
‘ Quart. Journ. Exp. Physiol.,’ vol. i, 1908. 
