242 OF THE PRIMARY TISSUES OF THE HUMAN BODY. 



the corrugation of the integuments of the scrotum, and that peculiar condition 

 of the general surface which is known as the "cutis anserina." The real nature 

 of its contractile element, however, has only been recently discovered by Prof. 

 Kblliker; who has found it to consist of "smooth" or non-striated muscular 

 fibre-cells (Fig. 99), which are united into fasciculi, and dispersed among the 

 other elements of the cutaneous substance. They are especially abundant in 

 the deeper part of the cutis of the scrotum, where they form a reticular layer 

 which is known as the "tunica dartos;" and also in the skin of the penis and 

 perineum, as well as in the nipple and areola. In other parts of the integu- 

 ment, they are especially connected with the hair-follicles ; and where these are 

 wanting, as on the palms of the hands and soles of the feet, there are no muscu- 

 lar fibre-cells. In the production of the " cutis anserina," which may be artifi- 

 cially induced by the application of the magneto-electric apparatus, these fibres 

 cause the protrusion of the hair-follicles, while they retract and depress the 

 intermediate cutaneous surface. 1 



237. The external surface of the Corium is elevated in many parts into 

 papillae or ridges, which, though representing the villi of mucous membranes, 

 have an entirely different office ; their special function being usually to receive 

 tactile impressions through the medium of the nerves with which they are fur- 

 nished, their size and number being proportional to the acuteness of the sensi- 

 bility possessed by different parts of the surface. In general, the papillae are 

 simple conical projections, the length of which is from about l-33d to l-22d of 

 a line ; but on the palm, sole, and nipple, they are mostly compound (that is, 

 they have several distinct summits), and measure from l-20th to l-10th of a line 

 in length. In these last situations, they are set very closely together in curvi- 

 linear ridges, which are marked at tolerably regular intervals by short transverse 

 furrows, into each of which the orifice of one of the sweat-glands discharges 

 itself. On some parts of the surface, however, the papillae are altogether want- 

 ing; and in the matrix of the nail, where they are as large and numerous as on 

 the palms of the hands, they serve an entirely different purpose, that of afford- 

 ing a more extended surface for the production of epidermic cells. The base- 

 ment membrane may be tolerably well made out by the definite boundary which 

 it affords to the components of the papillae ; but it is not distinguishable in a 

 like degree on the general surface of the Corium; and its presence there can only 

 be inferred from analogy, and from the existence of a fine film in that situation 

 in the embryo. The surface of the Corium likewise presents numerous depres- 

 sions, which are sometimes mere follicles, but sometimes tubuli of considerable 

 length. All these depressions are lined by cells, which are continuous with those 

 of the Epidermis ; but the function of these cells is very different in the several 

 varieties of the follicular organs. Thus, in the Hair-follicles, we find them 

 undergoing transformation into the substance of the hair, which is chemically 

 identical with that of the Epidermis itself; in the Sebaceous follicles, on the other 

 hand, they draw fatty matter from the blood, and set free this upon the surface 

 of the skin ; in the Cerumen-glands, they elaborate a waxy matter, which they 

 discharge on the integument lining the meatus of the ear ; in the Sudoriparous 

 glandulae, with which nearly every part of the surface is furnished, they are the 

 instruments of drawing off a large amount of watery fluid, which holds in solu- 

 tion a small proportion of effete organic compounds; and in the peculiar large 

 sudoriparous glandulae of the axillae, they further seem to eliminate from the 

 blood the peculiar Odorous secretion which is characteristic of that part. 3 The 

 Hair-follicles will be presently described in connection with the Epidermis ( 246) ; 



1 See Prof. Kolliker's Memoir on the "Smooth Muscular Fibre," in "Kolliker and Sei- 

 bold's Zeitschrift," 1849; and his " Mikroskopische Anatomic," band ii. pp. 13, 14. 



' See Prof. Horner in the " Amer. Journ. of Med. Sci.," Jan. 1846 ; and M. llobin, in 

 the "Ann. des Sci. Nat.," 3ieme eer., Zool., torn. iii. p. 380. 



