560 NOTES AND MEMORANDA. 



large fibres.^ This fact excludes the possibility of their being 

 connective-tissue corpuscles, from which they are in other 

 respects also quite different. Cells like these have been de- 

 scribed by various authors, e.g. by KoUiker, in the deeper 

 layers of the epidermis of the mouse -, by Tomsa, in human 

 skin ; by Langerhaus, in human skin after treatment with 

 chloride of gold ; by Kisselew, in the vesical epithelium ; by 

 Poncet, in the conjunctival epithelium of the ox. 



The other sort of cell, which is believed to be in connection 

 with nerve endings, is larger, coarsely granular, and rounded, 

 with a nucleus that is stained a deep brown by osmic acid. 

 These cells closely resemble the " Schleimzellen" described 

 by Leydig. 



The author does not speak positively of the connection of 

 these cells with nerve-iibres, and, indeed, his drawings do 

 not seem perfectly conclusive. He believes that a fine nerve- 

 fibril enters one of these granular ceils and runs up to the 

 nucleus, where it disappears in the granular cell-substance. 

 In one of his drawings such a connection is only apparent, 

 as he is himself somewhat inclined to admit. Leboucq con- 

 siders these cells to be quite analogous to those described by 

 Langerhaus in " Petromyzon Planeri" and to those which 

 the same author more recently figured, among the ordinary 

 epithelial cells of the Amphioxus, as tactile corpuscles — 

 ^•' Fiihlzellen" (' Archiv f. Mikros. Anat.,' Bd. xii. Heft 2). 



The paper concludes with the following short resume : 



1. The embryonic nerve is composed of a bundle of primi- 

 tive fibrils, developed out of the protoplasm of the embryonic 

 cells, or "Nervenbildungszellen." 



2. The derivatives of these formative cells, which surround 

 a bundle of primitive fibrils (an axis cylinder), form the 

 medullary sheath by a special metamorphosis. Each deriva- 

 tive of an embryonic cell provides for the development of 

 one segment of medulla; the point of contact of two neigh- 

 bouring cells forms a constriction of Ranvier. 



2. The terminal plexuses of nerve-fibres are in connection 

 with special corpuscles situated between the deeper epithelial 

 cells, the cement-substance here showing the same cha- 

 racters as that described by Ranvier in the human rete 

 Malpighii. 



4. Certain granular cells placed between the epithelial 

 elements seem also to be in connection with nerve-endings. 



1 I have described a similar connection of tlie terminal uerve fibres in the 

 tail of the tadpole, with branclied corpuscles which appear to be situated 

 beneath the epithelium. The terminal network of nerve-fibres which I 

 found in this locality is of far greater richness than that seen by M. 

 Leboucq. — E. Klein. 



