CoGHiLL, Structure of the Nerve Cell. 175 



fibrillae which most authors describe, van Gehuchten and Nelis 

 find a delicate, granular striatiou which they fail to connect certainly 

 with the cytoplasmic net. The granules of the striae are so arranged 

 as to give in some cases a cross-striated effect. 



Paton ('00) , in his studies of the neurofibrils of the cerebral cor- 

 tex of the pig, finds that the fibrillae of the axone run independently 

 of each other into the cell body, where they enter into a most intricate 

 net-work. He holds that the fibrillae of this net are continuous with 

 those of a pericellular reticulum, which he interpets as identical with 

 GoLGi's pericellular net. 



Paton believes that the fibrils are very quickly affected by post- 

 mortem granular disintegration which begins at the center of the cell. 

 He believes this fact may account for the view of certain authors that 

 fibrils exist only in in the apical process of the cell. 



Prentiss has recently published in this Journal his latest results 

 upon the neurofibrillar structures in Hirudo and Asticus. As to the gen- 

 eral arrangement of the fibrils in the cell body he confirms Apathy's 

 position. He concludes, however, that "Neither in vertebrates nor 

 in Crustacea do the neurofibrillae of the nerve cells show any marked 

 correlation in size and function." He believes that the differences in 

 size which Apathy observed are due to incomplete impregnation of the 

 fibrillae and perhaps to the cleaving together of smaller fibrillae in the 

 cell process. As to the relation of the fibril to the cell and its pro- 

 cesses Prentiss supports Bethe's view that fibrils may enter one pro- 

 cess and leave by another or by a collateral without coming into rela- 

 tion with the perikaryon itself. In Hirudo he finds a very limited fibril- 

 lar network in the neuropil. Such nets are more extensive in Astacus 

 but they are not diffuse in their relation. They put relatively few fib- 

 rillae into communication with each other. Prentiss considers that 

 his preparations tend to coirfirm Bethe's theory that the cells are not 

 the centers of nervous activity, and that the fibrillae are continuous 

 from cell to cell. 



PuGNAT, in his recent review on the finer structure of the nerve 

 cells, comes to the conclusion that the formed substance of the cyto- 

 plasm is a net, in some cases of fibrillae, in others of trabeculae, and 

 that this net is continuous with the fibrillae of the processes of the cell. 

 The relation which this net holds to the life aud function of the cell, 

 he thinks, can best be explained upon Bard's theory of "derived 

 substance." Although Pugnat does not accept the sharp chemical 

 and physical distinction between the protoplasm and the derived sub- 

 stance as Bard proposed, he believes that fibrillae are a product of the 



