TERMINATION OF THE " TACTILE NERVES." 53
PRELIMINARY NOTE ON THE MODE OF TERMINATION OF THE NERVE ENTERING INTO THE FORMATION OF THE "TACTILE CORPUSCLE."
BY A. R. ROBINSON, M.B,, L.R.C.P. & S., EDIN., Physician to the Skin Department, Demilt Dispensary, New York, etc.
THE present note is only intended as preliminary to a future discussion on some points in the histology of the skin, and is now published because pathological studies in which I am now en- gaged prevent the early completion of the whole article.
As is well known, the "tactile corpuscles" have always been re- garded as end-organs, — that is, it has been believed that the meduU lated nerve-fibres terminate within these corpuscles. Observers, however, have not agreed as to their mode of termination within this structure, and some of them have even maintained that it is not posi- tively proven that the nerve does terminate within the corpuscle. The question is a difficult one, but I have obtained specimens, four at present, which convince me that the nerve does not terminate within the corpuscle, but passes on into the rete Malpighii. The best corpuscles for observation are •the small ones, as in these a section ^'(MV^^'^'^ is more likely to include the entire /^/^-V^ "^ ' v^^fx upper extremity of the body than if A'^iiVnj^^^^--^^ * the corpuscle is large in size. Even r^DVVya^FC^^^^^ ^^ in a small corpuscle, however, unless e V^r'^'PJ J'^^P/( 9/OX the nerve passes onward in a direct iO/nfmM9iw^ level with the corpuscle, the nerve, jY^fJv^S^/fA^-- 7i in a perpendicular section, will be SK/^M^^^^^ cut more or less transversely, and it ^ vrW^Sl^l^^^ will be impossible to follow it from uK^'^^^ ^'^cr ^ the corpuscle into the rete. I believe ^Y^^^^^yP the nerve frequently, perhaps gener- /' 'y^'^ ^ ally, changes the direction of its ^ course after leaving the corpuscle to «, tactile corpuscle :/, nerve cut ob- , °, . ' . liquely ; c, apparent division of nerve; enter the rete, and hence we often ^, similar appearance;/, blood-vessel; see a transverse section of the nerve ^j.^'sdy"""' '^' """"= *'"*"'= cuttrans- at the upper part of the corpuscle. Even within the corpuscle the nerve generally pursues a more or less zigzag course, since we often see the latter cut across in several situations within the former.
In the accompanying figure is shown the mode of termination of the nerve-fibre as observed in one of my specimens. The section was colored with methaniline blue, and although gold is undoubt- edly better for studying the mode of termination of nerves, yet in this specimen the nerve was so easily to be seen that Dr. Satter- thwaite immediately recognized it without having his attention di-
