558 DES. GEOE&E AND FEANCES E. HOGGAST ON 



ending in shield-like bodies in the outer root-sheath of the hair- 

 follicle. Eedkel, in 1873, describes them as pear-shaped clubs 

 lying outside of the basement-membrane ; Mojsisovics, in 1876, 

 as oval and tactile cells in the outer root-sheath. Merkel, in 

 1876, describes them as oval and terminal tactile cells in the 

 lower layer of cells of the epithelial lining of the hair-follicle. 

 Bonnet, in 1878, speaks of them as end buds on the nerves after 

 these pierce through the basement-membrane. Finally, Eanvier, 

 in 1880, puts an entirely new interpretation upon the matter by 

 denying that the nerves terminate in cells, and asserting that 

 they are in connexion with tactile and terminal disks of nerve- 

 matter, concavo-convex in shape, which are closely applied to the 

 so-called terminal cells. A large number of these disks, he says, 

 are found in connexion with the same nerve-fibres, all of them lying 

 in the same direction and in the same relation to the tactile ter- 

 minal cells which they embrace, thus forming an arborization 

 having a certain elegance of form. Our figures 11 and 12 may 

 be taken to represent E-anvier's views on this question, although 

 we place a diflerent interpretation upon these drawings. It is 

 perfectly true that one part of the surface of the cell is stained 

 by gold much darker than the rest, which seems to argue strongly in 

 favour of Eanvier' s theory of tactile disks upon tactile cells ; and in 

 this respect fig. 12 appears almost unanswerable. On closer exa- 

 mination, however, we find many peculiarities incompatible with 

 his theory. In the first place, those blackened nerve-expausions 

 are not, as he states, all concavo-convex disks, nor have they all the 

 same direction {orientation), their concavity looking downwards. 

 In our fig. 11, PI. XIV., the cells a a have no disk at all, and 

 appear as if they had been placed upon the blackened nerve-fibril 

 iji a very irregular manner. In the second place, the special 

 blackening of one portion of the cell does not thereby prove that 

 that portion only of the ceU is nervous in character. In the same 

 figure it is seen that the portion c of the nerve-fibril intervening 

 between where tlie myeline ceases at h and the cells at a, is equally 

 almost colourless ; while the portion d further on amongst the 

 terminal cells is stained jet-black ; yet no one would for a moment 

 argue that the portion c is less nervous in character than the 

 portion d. The cause of the special blackening in one spot in 

 gold preparation is as yet a puzzle to us, like numerous other 

 peculiarities in the behaviour of this notoriously uncertain re- 

 agent ; but, from its irregular effects on many of our prepara- 



