4 EISEN. [Vol. XVII. 



which were made the material for this memoir. After- 

 wards I was of course able to supplement them with less 

 favorable material from specimens collected at other times. 

 In size the adult testis is about five millimeters long by one 

 millimeter wide. It consists of only one single lobe, undivided 

 and of cylindrical shape. In the central parts of this lobe 

 are the ripe spermatozoa, while the other cells are found 

 arranged on either side in the direction of the long diameter 

 of the testis. The four testes were sectioned longitudinally, 

 thus affording a comprehensive view of the arrangement of the 

 different cells. 



It is with much pleasure that I here acknowledge my indebt- 

 edness to my esteemed friend. Dr. W. J. V. Osterhout, of 

 the University of California, for many valuable suggestions and 

 for assistance in correcting MS. and proof. 



II. Methods of Ixvestigation. 



Fixatives. 



The first investigations were made on testes fixed with the 

 classical fixatives — Flemming's chromo-aceto-osmic mixture 

 and the platino-aceto-osmic mixture of Hermann, used in various 

 strengths, with or without admixture of water. Heidenhain's 

 corrosive-sublimate-acetic was also tried, both with and with- 

 out addition of formalin. Experiments were also made with a 

 number of other fixatives, such as mixtures of Flemming's and 

 Hermann's with corrosive-sublimate and palladium-chloride. 

 Vanadium-chloride, uranium-chloride, and osmium-chloride were 

 also experimented with, all of which, with the exception of the 

 last, proved of no value. I soon satisfied myself that any mix- 

 ture containing either platinum-chloride or osmic acid, or both, 

 would completely ruin several of the outer rows of cells, mak- 

 ing them unfit for microscopic research. As the testes of 

 Batrachoseps are so very small and possess only a few rows of 

 cells, none of the above-mentioned fixatives could thus be used. 

 Platinum-chloride is even more injurious than osmic acid ; while 

 the latter destroys the chromatin, the former ruins the finer 

 structure of the cytoplasm. Although by the employment of 



