2 Journal of Comparative Neurology. 



In all researches on the central nervous system by means 

 of impregnations the elements of the cerebellum, as is well 

 known, offer the greatest difficulties. A considerable number 

 of preparations are usually required to demonstrate all the 

 elements of this organ. This peculiarity appears to have pre- 

 sented itself also in the preparations at Sauerbeck's service, as, 

 judging from his figures, all the other parts of the brain seem 

 to have been much more completely and certainly impregnated 

 than the cerebellum. Thus Sauerbeck was able to demonstrate 

 only Purkinje cells and ependyma elements in the cerebellum. He 

 has, indeed, on the ground of stained preparations confirmed the 

 presence of a molecular and a granular layer in agreement with 

 earlier authors ( Viault (8), Sanders (3), and Rohon (2) ), yet he 

 did not succeed with Golgi preparations in learning anything of 

 the elements constituting them. Thus there remain in reserve 

 many important points for further investigation to determine. 

 As I have several years since directed my special attention to 

 the morphology of the cerebellum and contemplate subjecting 

 this part of the brain in all the vertebrate types to a compara- 

 tive anatomical and comparative embryological investigation, 

 the present gap in our knowledge of the selachian brain, so im- 

 portant for my purpose, became so much the more perceptible 

 to me. It was natural, therefore, that I should eagerly seize 

 the opportunity, presenting itself to me in Woods Hole, of fill- 

 ing in, as far as lay in my power, these gaps by means of 

 suitable investigations. My efforts toward this end were 

 attended with some success and I take the hberty to report 

 briefly upon them in the following. 



Although I propose to publish here the results obtained 

 from silver preparations only, yet I might for general orienta- 

 tion, preface this with a few words upon the morphology of 

 the selachian brain. In so doing I confine myself to that of 

 Mustelus vulgaris ( Galeus cards ) from which species my 

 Golgi preparations were exclusively made. 



As with most of the Selachii, in Mustelus the cerebellum 

 is greatly developed and is traversed by numerous transverse' 

 folds. It might from this appear that the cerebellum of the 



