OF THE SKIN. 



139 



the skin around the hair sacs by which their apertures are protruded 

 conically, is explained simply by the existence of the muscles which I 

 discovered, and which pass obliquely from the superficial part of the 

 cutis down to the hair sacs, and when they act, extrude the sacs, and 

 retract those portions of the skin whence they arise. The assumption 

 of a contractile connective tissue in the skin, as well as in other parts, 

 I must repudiate here, as I have already done (Mittheil. der Zuricher 

 Gresellschaft, 1847, p. 27), because the smooth muscles, which can be 

 microscopically demonstrated in the skin, and whose contraction by 

 galvanism may be experimentally shown, sufficiently account for all the 

 contractile phenomena which it exhibits. 



B. EPIDERMIS. 



40. The corium is everywhere covered by a semitransparent mem- 

 brane formed wholly of cells, and containing neither vessels nor nerves, 

 the epidermis, which applies itself exactly to all the elevations and 



-6' 



depressions, and which accordingly upon its inner surface presents an 

 exact cast of the outer surface of the corium^ the convexities and con- 

 cavities of course being reversed. Upon its outer surface, also, the 

 epidermis, to some extent, represents the form of the corium since the 



FIG. 55^2. Surface of the palm, from within: a, ridge answering to the groove between 

 the ridges of the cutis ; 6, a similar one corresponding with the cleft between the rows of 

 papillae; c, sweat ducts; d, broader points of insertion of these into the epidermis ; e, depres- 

 sions for the simple and compound papillae. 



