58 Journal of Comparative Neurology. 



The problem of their ental destination is probably involved with 

 that of the ganglionic plexus, to be described. 



In the skin from the head of the frog treated with the 

 silver method, there is found at the base of the corium, a rela- 

 tively thick stratum containing a most intricate plexus of gang- 

 lion-Hke cells with their fibers. This plexus is to be distin- 

 guished from that which was mentioned in connection with the 

 ental course of the fibers from the terminal cells. The latter 

 lies farther entad, and is composed wholly of nerve bundles 

 with their ramifications. The ganglionic plexus occupies the 

 base of the corium. In some instances the elements of the two 

 may mingle, but their structures are wholly different. In many 

 instances the fibers of the ganglionic plexus are so numerous 

 that the central portion of the stratum becomes perfectly opaque 

 with the stain, while the ental and ectal edges show a purely 

 fibrous arrangement. In other localities of the stratum there 

 are blackened areas showing the structure just described but 

 united with each other by numerous plainly differentiated fibers. 

 In still other instances there are large areas in which the struc- 

 ture is purely fibrous. (Fig. ii and 12.) At first sight there 

 seemed to be a possibility that this appearance might be due to 

 the presence of extensive pigmentation; but examination of sec- 

 tions of the skin from the same region fixed in the chrom-acetic 

 acid and Flemming solutions and stained as previously men- 

 tioned showed no pigmentation whatever in this part of the skin, 

 while sections treated in methylene blue showed that there 

 might be occasionally a granular pigmentation in this region 

 and that typical chromatophores occur very seldom. By refer- 

 ence again to the sections treated with the Golgi method, it 

 was found that the stratum impregnated universally had a 

 fibrous structure in part, and that, in relatively large areas 

 where there was the clearest differentiation of the stain, the 

 structure was purely fibrous. In the latter instance, if the ap- 

 pearance in question were due to the impregnation of chroma- 

 tophore elements, it would be expected that the stain would 

 first select the body of the chromatophore and not bring to 

 light its phenominally long ramifications, if the fibers could 



