578 DBS. GEOEGE AND FEANCES E. HOGGAJST ON 



mised reasoning. In doing so, we are still true to our text of tlie 

 organ of Eimer ; for Merkel's functional conclusions concern spe- 

 cially the fibrils of the outer circle, the central fibrils, and the nerve- 

 cells at the base of the epidermic downgrowth of the organ. 



MerheVs Sypothesis of the different Functions of certain Nerve- 

 elements in the Skin. 

 In the ' Archiv f iir mikroscopische Anatomie ' for 1876 Pro- 

 fessor Merkel, of Rostock, published an account of some peculiar 

 groups of cells which he had discovered on certain of the inter- 

 papillary epidermic downgrowths. Some of these cells appeared 

 to be in direct continuation with some of the meduUated nerves 

 in the skin ; and he therefore named them terminal tactile nerve- 

 cells. These cells he held to be identical with the terminal cells 

 found on the feeler hairs of mammals that we have already de- 

 scribed, and an account of which had previously been published 

 by Sertoli, Dietl, and others. He even extended his comparison 

 of these cells to the cells composing the touch-bodies in the 

 fingers of Man, and to the more simple structures of the same 

 kind found in the beak and tongue of Birds. After giving a full 

 account of these structures, with copious illustrations, from his 

 point of view, he concludes his article with the following opinions 

 as to the comparative functions of these cells and of the intra- 

 epidermic nerves : — " I may therefore express as a fact, tha,t only 

 one kind of nerve-termination in cells occurs in the skin, that is 

 the termination in tactile cells .... In the skin of Birds and 

 Mammals two entirely difiereut kinds of terminations, differing 

 in their original plan of construction, occur side by side — the 

 terminations in tactile cells and the terminations in free ends " 

 (i. e. intraejDithelial fibrils). "One feels inclined to make an 

 attempt to utilize the difierence physiologically ; and I believe, 

 indeed, that I have grounds for considering the terminations in 

 cells as the real tactile nerves, and the free ends, on the other 

 hand, as nerves of temperature." 



To these opinions of Professor Merkel we are entirely oj)posed. 

 We have, indeed, discovered one circumstance which completely 

 "demolishes his hypothesis of separate functions for the two kinds 

 of endings he describes ; and that is that his so-called terminal 

 cells and his free endings belong to one and the same nerve- 

 system, and are continuous with each other, so that whatever 

 sensorial function pertains to the one must equally belong to 



