RECENT EESEAECHES ON SPERMATOGENESIS. 325 



connection between this cell and the " mother cell " with its 

 '^ principal nucleus " of the Mollusca. Further examination 

 caused him to abandon this view, as it was possible to find 

 distinct gradations between this cell and the " male ovules ;" 

 and here is the chief point where his observations and mine 

 disagree. Undoubtedly these granular cells do exist and give 

 rise to the " male ovules " (spermatospores) forming part of 

 the testicular epithelium, but, according to my view of the 

 matter, the cells which are carried back with the young sperma- 

 tozoa are distinct from these and are, as it were, left behind 

 during the formation of the vesicle, being homologous and 

 analogous with the blastophoral cell of the Mollusca, and, like 

 that, undergoing a process of fatty degeneration. For, if a 

 testis be taken in the spring, at the right time, after the dis- 

 charge of the spermatozoa there will be found in the testicular 

 sacs a number of cells whose nuclei are disintegrated into 

 coloured granules, whose surface is marked with striae, repre- 

 senting the points of attachment of the spermatozoa, and whose 

 substance contains many fat granules, obviously representing 

 the degeneration of the supporting cell. This view of the 

 existence of the blastophoral cell and explanation of its origin 

 and function will be seen to receive considerable support from 

 the study of the spermatogenesis of a group in many ways 

 allied to the Amphibia, viz. the Selachians, to which I will 

 now proceed. 



The most recent account of the development of the sper- 

 matozoa in the Selachians is contained in the ' Journal de I'Anat. 

 et de la Physiol., 'No. 4, 1882, in a paper by M. G. Hermann. 



The testis of the Selachians is remarkable for its simplicity 

 and points of resemblance to the ovary, the primitive germinal 

 cells, forming the germinal epithelium, sink into the subjacent 

 tissue in chains or groups (cordons de Pfliiger) in the same 

 way as they do in the ovary ; but instead of forming Graafian 

 follicles they make up the anipullse in which the germinal 

 cells, male ovules, or spermatospores undergo changes which 

 result in the production of a crop of spermatozoa, and when 

 this process is over, the whole follicle or ampulla atrophies 



VOL. .\XI1I. NEW SEiv. Y 



