CTJTANEOTJS NEEVE-TEEMINATIONS IN MAMMALS. 581 



bodies, and therefore confine ourselves to the one structure in ques- 

 tion. Upon this Professor Eanvier, in his preliminary communica- 

 tion to the Academic des Sciences in December 1S80, says : — " On 

 the lower surface of the epidermic downgrowths of the snout of the 

 Pigthere exist, according to Merkel, amongst the ordinary epithelial 

 cells, certain special cells in which the tactile nerves end. In 

 reality these nerves, after having penetrated within the epithelium, 

 divide, subdivide, and form, on the cells of Merkel, little concavo- 

 convex disks, which appear semilunar when they are seen in pro- 

 file in sections made perpendicular to the surface of the integu- 

 ment, but stellate and anastomosing by their prolongations when 

 they are examined from their largest surface. The tactile disks 

 of the Pig's snout have apparently the same signification as the 

 tactile disks of the Palmipedes." Apart from the dual condition 

 of cells and disks, Professor Ranvier's descriptions are a great 

 advance upon Merkel, Bonnet, and others in showing, not that a 

 medullated nerve ended in a cell, but that it ended in a great 

 number of elements connected one with another by fine fibrous 

 continuations. The only difference in this respect between our 

 views and his is, that his nerve-disks are described as being stel- 

 late, while we hold that it is the cells that are stellate ; but the 

 continuations of his disks with the free intraepidermic endings 

 he has not observed. As to function, his words show that he 

 agrees with Merkel, certainly not with us. 



Proofs that the Nerve-cells and Intraepidermic Fibrils are 

 contimious. 

 The distinguished men who have debated the previous question 

 agree in recommending the snout of the Pig as the best object 

 in which these groups of nerve-cells may be studied. In this 

 we think that they have been unfortunate ; for although the 

 groups there are much more common and easily demonstrated 

 than elsewhere, yet, whether it be owing to the fineness of the 

 fibrils uniting the cells or the size and number of the cells them- 

 selves, their whole history cannot be so easily traced as in some 

 other animals. After searching in a large number of animals, 

 we find none so suitable for this purpose as the Horse ; and our 

 figures 19 and 21, from that animal, put a different interpreta- 

 tion upon those cells from any that has hitherto been suggested. 

 That group is only one of scores of similar preparations in our 

 possession, which show the same junction of cells with intra- 



