CUTANEOUS NEEVE-TEBMINATIONS IN MAMMALS. 577 



we agree witli Ranvier, has entirely ceased ; and even although 

 the connexion of a few of these with the plexus at a certain point 

 were severed, not only would that portion of the plexus not dege- 

 nerate, but through its plentiful connexions in the plexus it could 

 communicate, through other remaining nerves a short distance 

 away, with the central nerve-centres. On the other surface, that 

 is to say the peripheral or epidermic surface of the subepidermic 

 nerve- system, branches may be given off into the epidermis ; and 

 it is a point which no previous observers seem to have noticed, 

 that the intraepidermic nerve-fibrils are not given off fi-om me- 

 dullated nerves (the apparent exception of the inner circle of 

 fibrils in the organ of Eimer being an abnormal condition, although 

 depended upon by Eanvier), but from the subepidermic nerve- 

 system, of which they are only branches. In hundreds of speci- 

 mens which we have carefully examined, we have never yet met 

 with a meduUated nerve passing up to the epidermis and giving 

 off non-medullated fibrils into the epidermis, as Eanvier's theory 

 would imply ; but at the same time there is no reason why, as 

 rare exceptions, such a condition may not be found, as indeed has 

 been drawn by Merkel : but the cause of this exception will be 

 clearly shown hereafter. 



But we are prepared to prove, what may appear to nerve- 

 histologists the most astounding part of our proposition, that 

 the intraepidermic nerve-fibrils do not penetrate into the epi- 

 dermis of their own accord, but are dragged there against their 

 will and against their tendency to lateral direction of growth — 

 that, indeed, the free ending of a fibril within the epidermis is an 

 accident or a mutilation, resulting from the breakage of one of 

 the endless strands or fibrils of the subepidermic nerve-system 

 which has become entangled among the epidermic cells, and that 

 such free endings, instead of having any special function, such as 

 has hitherto been attributed to them, are probably, by the very 

 act of breakage which made them free endings, deprived of every 

 function. The preparations and reasoning by which we shall 

 prove our novel proposition just referred to, while negativing 

 Professor Hanvier's hypothesis of growth, and showing our 

 hypothesis of lateral direction of growth to be true of the peri- 

 pheral subepidermic system of nerves, will also negative the im- 

 portant theories of Professor Merkel and others as to the special 

 function of certain portions of the nerve-terminal apparatus in the 

 skin. These we had better explain before entering upon om* pro- 



LINN. JOUEN. ZOOLOGY. — VOL, XVI. 43 



