623 



laufenden, ringförmigen Gang vorstellt, kreisförmig eingeschlossen ist. 

 Mit ihm steht es durch einen dorsalwärts gelegenen, von 6 Schließzellen 

 umstellten Porus in Verbindung. Die Ausmündung erfolgt durch einen 

 kurzen ectodermalen Harnleiter. Zimmer beschreibt in seiner Arbeit 

 die Antennendrüse als ringförmig geschlossenen Schlauch, ohne ein 

 Endsäckchen zu erwähnen. 

 Wien, 4. Februar 1913. 



7. On the Effect of Castration on the Thumb of the Frog. (Rana fusca.) 



By Geoffrey Smith, M.A., Fellow of New College, Oxford. 

 (With 3 figures.) 



eingeg. 10. Februar 1913. 



As the result of experiments upon the Frog, published under the 

 title of Studies in the Experimental Analysis of Sex , Part 8 , in the 

 Quarterly Journal of Microscopical Science (1), Dr. Schuster and I 

 criticised the conclusions which Dr. Nussbaum(2) and Prof. Meisen- 

 heimer(3) have drawn from similar experiments, and expressed the 

 opinion that the experiments of these authors were not sufficient to prove 

 that the growth of the papillae on the thumb of a castrated frog could 

 be induced by the injection of testis (or ovarian) extracts. 



I have lately obtained further results which show conclusively that 

 our sceptical attitude was justified, and that it is extremely improbable 

 that the growth of the papillae recorded by these authors was in any 

 instance caused by the injections employed. At the same time the new 

 results I have obtained necessitate a slight modification of the view 

 which v/as given in our former paper of the cycle of changes through 

 which the thumb goes. 



The crucial experiment which has just come to a successful end is 

 as follows. A certain male specimen of Rana fusca, weighing about 

 15 grs, was completely castrated on December 15th, 1911. At this time 

 the thumb showed a well-developed pad of brown papillae which had 

 not quite obtained their full size or pigmentation. The appearance of 

 the thumb under a dissecting microscope is shown in fig. 1, and some of 

 the papillae under Zeiss 2AA are shown in fig. la. 



From the time of castration the thumb was inspected from time to 

 time and no perceptible change appeared in it until May and June 1912 

 when it appeared that the papillae were greatly reduced. The disap- 

 pearance of the papillae continued during the summer and by September 

 all traces of papillae had completely disappeared from both thumbs. To 

 make absolutely sure that the thumbs were perfectly smooth one of them 

 was cut off and examined with great care all over under the microscope 



