214 THE SKIN. 



tough framework of interlaced connective tissue fibres, with blood- 

 vessels and lymphatics. The fibres are chiefly of the white variety, such 

 as constitute the chief part of the fibrous and areolar tissues, and are 

 arranged in stout interlacing bundles, except at and near the surface, 

 where the texture of the corium becomes very fine.* Witli these are 

 mixed yellow or elastic fibres, which vary in amount in diflFerent parts, 

 but in all cases are present in smaller proportion than the former kind ; 

 also connective tissue corpuscles, fusiform or ramified, and for the most 

 part reticularly anastomosing. The interlacement becomes much 

 closer and finer towards the free surface of the corium, and there the 

 fibres can be discovered only by teasing out the tissue, which often 

 acquires an almost homogeneous aspect. Towards the attached surface, 

 on "the other hand, the texture becomes much more open, with larger 

 and larger meshes, in which lumps of fat and the small sudatory glands 

 are lodged ; and thus the fibrous part of the skin, becoming more and 

 more lax and more mixed with fat, blends gradually with the subcu- 

 taneous areolar tissue, to which it is allied in elementary constitution. 

 Bundles of plain muscular tissue are distributed in the substance of the 

 corium wherever hairs occur ; and their connection with the latter will 

 be afterwards explained. Muscular bundles of the same kind are found 

 in the subcutaneous tissue of the scrotum, penis, perineum, and areola 

 of the nipple, as well as in the nipple itself. They join to form reticular 

 superimposed layers, which are separated from the parts beneath by 

 a stratum of simple lax areolar tissue, but towards the surface they 

 are immediately applied to the corium. In the areola they are disposed 

 circularly. 



In consequence of this gradual transition of the corium into the sub- 

 jacent tissue, its thickness cannot be assigned with perfect precision. 

 It is generally said to measure from a quarter of a line or less to nearly 

 a line and a half. As a general rule, it is thicker on the posterior 

 aspect of the head, neck, and trunk, than in front ; and thicker on the 

 outer than on the inner side of the limbs. The corium, as well as the 

 cuticle, is remarkably thick on the soles of the feet and palms of the 

 hands. The skin of the female is thinner than that of the male. 



For convenience of description it is not unusual to speak of the 

 corium as consisting of two layers, the " reticular " and the " papillary." 

 The former, the more deeply seated, takes no part in the construction of 

 the papillae, but contains in its meshes hair follicles, cutaneous glands, 

 and fat. The latter is divided into papillse, and receives only the upper 

 portion of the hair-follicles and glands, together with the terminal ex- 

 pansion of the vessels and nerves. 



The free surface of the corium is marked in various places with larger 

 or smaller furrows, which also affect the superjacent cuticle. The 

 larger of them are seen opposite the flexures of the joints, as those so 

 well known in the palm of the hand and at the joints of the fingers. 

 The finer furrows intersect each other at various angles, and may be 

 seen almost all over the surface ; they are very conspicuous on the back 

 of the hands. These furrows are not merely the consequence of the 

 frequent folding of the skin by the action of muscles or the bending of 

 joints, for they exist in the foetus. The wrinkles of old persons are of 



* A memlrana proprk', or Imsement-membrane, is sometimes described as bounding tlie 

 corium snpeiliclalJy like that found in tbe mucous membranes. 



