338 DR. E. KLEIN. 



Stained in picrocarmine and ha?matoxylin, as it assumes 

 a distinct tint. As shown in fig. 2S, h, it extends a certain 

 distance beyond the poles of" the nucleus. In some places the 

 expansion of the ground plate is much greater at one side of 

 the nucleus than at the other. To each nucleus, therefore, 

 corresponds a cell-plate, and consequently we find a greater 

 number of cell-plates, the thicker tlie nerve-fibres. A 

 microscopic nerve trunk of the mesentery of batrachian 

 and other animals exhibits, by the aid of silver-staining, the 

 ])r(sence of a complete envelope of nucleated endothelial 

 plates. (Axel Key and Retzius, Ranvier.) 



The nucleus contains iti all instances a beautiful network 

 of fibrils, and in this respect it is second to no nucleus of 

 any other kind. 



A point that deserves careful consideration is the relation 

 of the fibre-bundle, i.e. the axis cylinder, to the intranuclear 

 network. I have examined the nerve fibres in my specimens 

 with great attention, and I have failed to obtain any evidence 

 of a connection of the two ; on the contrary, in most in- 

 stances I am able to follow the axis cylinder along one or 

 the other side of the nucleus beyond this latter, and there 

 is every reason to regard this ccmdition as the rule. If in 

 an isolated instance the appearances are against it, I can 

 easily account for it. The reason is this : the nucleated 

 cell-plate, which at intervals ensheathes tlie axis cylinder, 

 does not consist merely uf the hyaline ground- plate and nu- 

 cleus, as mentioned above, but possesses fibres, which I will 

 call investing fibres ; they are in connection with tJie intranu- 

 clear network and pass beyond the ground-plate, they follow 

 closely the axis cylinder and appear to be twisted round it so 

 as to actasa the sheath for the sections between two neigh- 

 bouring cell-plates. If, then, in one or the other instance it 

 would appear as if the axis cylinder were in connection 

 with the intranuclear network, these investing fibres must 

 not be forgotten. I have not represented these fibres in 

 figure 23, because they were not distinctly differentiated in 

 the nerve-fibre delineated in this figure, which is a faithful 

 rcuidering of the appearances observed in this particular 

 nerve-fibre; but there are others in which 1 have seen the 

 investing fibres with sufficient distinctness. Thus, there 

 exists a complete analogy between these cell-plates and the 

 connective-tissue corpuscles described in a former paragraph, 

 for in both we distinguish a hyaline ground-plate from the 

 fibres which, on the one hand, are in connection with the in- 

 tranuclear network, and, on the oiher hand, pass as the pro- 

 cesses l)i'}on(l the limits of the ground-plati'. The ililietciice 



