476 



THE TISSUES. 



I. THE SKIN. 



1. The corium of the skin, or innermost layer, constitutes the 

 greater part of its entire thickness in most parts of the body ; and 



this alone is converted 



Fi S- 316 - into leather when the 



skins of the lower ani- 

 mals are tanned. Its re- 

 lation to the basement- 

 membrane and the epi- 

 thelium is shown in a 

 vertical section of the 

 skin (Fig. 317); which 

 also shows a sweat gland 

 in the subcutaneous areo- 

 lar tissue, or superficial 

 fascia, described on page 

 290. It is a tough, slight- 

 ly elastic membrane, com- 

 posed of white and yellow 

 fibrous (areolar) tissue ; to 

 which must also be added 

 smooth muscular fibres, 

 bloodvessels, nerves, and 

 lymphatics, in great abun- 

 dance. In the inner por- 

 tions of the corium, the 

 fibres are interwoven in a 

 manner to give indica- 

 tions of lamination. The 

 elastic fibres abound in 

 the corium; but much 

 more in the subcutane- 

 ous areolar tissue. The 

 smooth muscular fibres also 

 abound in some portions 

 of the latter, constituting 

 the dartos, so called, under the skin of the scrotum; and a similar 

 layer under the skin of the prepuce, of the perineum, and the ante- 



Typical forms of glands. A. Simple glands ; a, b, c, as in 

 the last figure ; g, follicle or follicular gland ; 7i, sacculus, 

 or saccular gland ; i, tubular gland, the tube coiled up. B. 

 Simple racemose glands ; fc, of tubular, and I of saccular 

 form. c. Compound racemose glands ; ra, entire gland ; 

 showing branched duct and lobular structure ; ri, a lobule 

 detached, with o, branch of duct proceeding from it. D. 

 Compound tubular gland. 



