558 v. a. e. crew and honor b. fell 



Methods. 



With the exception of the goat the material was already 

 fixed when received by us. The testis of the goat was fixed 

 in Zenker's fluid, that of the rabbit in Bouin's fluid, and that 

 of the frog and of the cat in 10 per cent, formalin. 



The specimens were embedded in paraffin wax and sections 

 were cut at 5-6/^. We employed the following stains : eosin 

 and Delafield's haematoxylin, Haidenhain's iron haema- 

 toxylin, Mallory's and Van Gieson's. A good method for 

 displaying the interstitial cells was to stain with iron haema- 

 toxylin in the usual w^ay and counter-stain with Van Gieson's. 



The sections of the frog's gonad, which had been used in 

 previous research, were stained with Delafield's haematoxylin 

 and Bismarck bro%\ii. 



The coloured drawings were made with the aid of a camera 

 lucida. With the exception of fig. 17, for which a Koristka 

 1/12 oil immersion lens was employed, they were all drawn 

 to the same scale with a Zeiss no. 7 objective. 



Description of the Undescended Testis of a Goat. 



The specimen was obtained from an adult goat whose sexual 

 behaviour was sometimes of the male and at other times of 

 the female type. The internal and external genitalia were also 

 intersexual in character. The testes were discovered in the 

 region of the external inguinal ring embedded in the sub- 

 cutaneous tissue of the ventral body-wall and surrounded by 

 a thick investment of fat. 



General Structure of the Gonad. 



Seminiferous Tubules. — The seminiferous tubules 

 show greater degeneration than any other tissue in the gonad. 

 Degeneration has not proceeded at a uniform rate throughout 

 the testis, and the tubules maj" be described in three classes 

 according to the stage which the atrophic changes have reached. 



Class A. — Comparatively normal tubules. The cross- 



