ScHAPER, Stnictiire of Selachian Cerebellum. g 



expressed in the higher vertebrates make the abov^ division 

 desirable from practical grounds. 



I have entered into a discussion of this point more at 

 length here to secure a basis for the elucidation of the relations 

 which we have encountered in the above described cells of the 

 molecular layer of the selachian cerebellum. As we have seen, 

 the axis-cylinders of none of these cells exhibit the typical con- 

 duct of those of the basket cells ; never were tassel-like term- 

 inal arborizations demonstrable. In certain cells lying in the 

 deeper zone of the molecular layer, one sees here and there 

 isolated terminal branches penetrate between the bodies of the 

 Purkinje cells but there cannot be said to be the intimate and 

 extensive contact-relation to the latter that there is in the 

 case of the basket cells. Besides this, there are usually 

 present on such axis-cylinders numerous other terminal branches 

 which do not proceed towards the Purkinje cells. In the ma- 

 jority of the cells of the molecular layer we saw the ramifica- 

 tions of the axis-cylinder spread out in all directions without 

 ever entering into any relation with the bodies of the Purkinje 

 cells. This all cells observed by vie in the molecular layer of tlie 

 selachian cerebellum more or less resemble — apart from a slighter 

 complexity in the ramification of both dendrites and axis-cylinder 

 — those cells lohich Smirnozv has recently described in man and the 

 higher vertebrates and distingnished from the true basket cells. If 

 we now, as mentioned above, will regard the basket cells merely 

 as a particular specialization of the cells of the molecular layer, 

 this specialization has not yet appeared in the cerebellum of 

 the Selachii ; these cells are here still in a more primitive or phylo- 

 genetically younger stage of development. I might use this op- 

 portunity to mention that I likewise have not hitherto succeeded 

 in demonstrating true basket cells in the molecular layer of the 

 cerebellum of Teleosts (5). Probably the state of affairs here 

 is similar to that in the Selachii. 



Nerve-cells of the Granular Layer. 



The granular layer in the cerebellum of Selachii has hith- 

 erto been established as such and homologized with the cor- 



