CTJTANEOTTS NERVE-TERMINATIOTirS IN MA.MMALS. 585 



as at n, lig. 23, Plate XVI., from the nose of the Bullock, and car- 

 ried away, one by one, into the epidermis ; but if the connecting 

 fibrils are strong, we may find the whole ganglionic group carried 

 wholesale into the epidermic stream. The Horse seems to be 

 a peculiarly suitable animal in which to watch this process, on 

 account of the strength of the connecting fibrils ; and among our 

 preparations from this animal we have every stage in the process 

 represented, from the first entanglement of the ganglion to the 

 point when the rear cells of the ganglionic group are about to 

 disappear (lost in the stratum granulosum) near the free surface 

 of the epidermis, as shown in fig. 21, Plate XY. It is, however, 

 generally as broken-off" solitary cells that these are seen in other 

 animals, more especially in inflammatory conditions of the skin, 

 when such cells abound ; and it is these cells, due to the process 

 of entanglement which we have described, that are called the 

 cells of Langerhans. 



During the early days of the gold process, Langerhans de- 

 scribed, in Virchow's 'Archiv' for 1868, certain peculiar branched 

 and deeply stained cells within the epidermis of Man, which he 

 considered to be nervous in their nature. Two years afterwards 

 Eberth took up the question, and, while confirming Langerhans's 

 discovery, denied the nervous character of these cells, which he 

 supposed were either pigment-cells or wandering cells. Since 

 then every investigator in this department has made his guess as 

 to the character of these cells. Some, like Merkel, have supposed 

 them to be unpigmented pigment-cells ; others (Krause for ex- 

 ample) supposed them to be those apocryphal structures, the 

 radicles of the lymphatics ; but the greater number (including 

 Arnstein, Bonnet, and E-anvier) accept Eberth's last suggestion, 

 and consider them to be wandering cells. All deny their nervous 

 nature ; but it is to be hoped that after the explanations we have 

 given their character will be no longer doubtful, and that the 

 hypothesis of their discoverer fourteen years ago will be accepted 

 as correct. With reference to auy identity between them and 

 the cells of Merkel, the latter histologist declared that his cells 

 were certainly not branched, while Bonnet gives drawings of the 

 two in the same spot, and thinks that he disposes of their iden- 

 tity by showing that Merkel's cells are oval and Langerhans's 

 cells branched. He evidently was unaware that Merkel's cells 

 when seen broadside are branched, and that when they are 

 broken off" and distorted by the pressure of the epidermic cells 



