CTTTATTEOTTS NERVE-TERMINATIONS IN MAMMALS. 558 



anatomical and physiological grounds, best fitted still to represent 

 something different from ordinary hairs. If the observers who 

 wished to make the existence or non-existence of a blood-sinus 

 around the hair-follicle (a, fig. 13, Plate XIV.) the basis for a new 

 name, had given their attention to the character of the muscles 

 attached to those difterent hairs, they might probably have found 

 reasons for letting the terms remaia as at present understood. 

 In the ordinary hairs the muscles which are attached to the base 

 are of the smooth or iuvoluntary type ; and these, although they 

 act upon the hair under the influence of temperature, moisture, 

 electricity, &c., causing goose-skin and similar appearances, are 

 yet completely beyond the control of the will. In the feelers, 

 however, these muscles are of the striated or voluntary type, 

 which gives the animal the power of moving the feelers at will in 

 different directions, so that it may acquire by touch timely notice 

 of the proximity of any neighbouring object. In this respect the 

 feeler is a voluntary and active sensorial organ, while the ordinary 

 hair is merely an involuntary and passive one ; and for this reason 

 we shall continue to use the term feeler in the sense hitherto 

 accepted, as distinguishing it from ordinary hairs, bearing in mind 

 also that this, like every other differential feature between hairs, 

 passes insensibly into the opposite condition. 



Of the other anatomical diftereuces between feelers and ordinary 

 hairs, or of the anatomical elements composing either, we intend to 

 say as little as possible, where the question does not interfere with 

 our present subject, which is a description of the nerve-arrange- 

 ments on hairs. For the benefit, however, of our non-anatomical 

 readers, we submit a short description of the hair- apparatus general 

 enough to apply to all hairs. The hair-follicle is simply a depression 

 in the skin, passing down like a well, whose sides are almost perpen- 

 dicular to the outer surface of the skin. It is lined with layers 

 of cells (e, fig. 13, Plate XIV.) similar to and continuous with those 

 of the epidermis. Surrounding this epidermic lining we have a 

 thin layer of specicilly clear gelatine, called the basement mem- 

 brane {b, fig. 13, Plate XIV.), which is continuous with that of 

 the surface of the skin, it being in turn surrounded by the general 

 gelatinous tissue of the dermis, or skin proper. At the bottom 

 of the follicle or well there may or may not be a papilla, covered 

 also with epidermic cells ; from this the hair itself grows, being 

 formed solely of epidermic cells arranged iu layers, and showing 

 a gi'eat variety iu appearaucc and substauce in different animals 



