ORGAN OF TOUCH. 521 



maxillary glands : from the sides of the cheeks it passes through the 

 openings of Stenon's * ducts to the parotid glands : in the fauces, it 

 forms the assemblage of follicles called tonsils, and may be thence 

 traced downwards into the larynx and pharynx, where it is continuous 

 with the general gastro-pulmonary mucous membrane. 



Beneath the mucous membrane of the mouth are a number of small 

 glandular granules, which pour their secretion upon the surface. A 

 considerable number of them are situated within the lips, in the 

 palate, and in the floor of the mouth. They are named from the 

 position which they may chance to occupy, labial, palatine glands, &c. 



ORGAN OF TOUCH. 



The Skin is the exterior investment of the body, which it serves to 

 cover and protect. It is continuous at the apertures of the internal 

 cavities with the lining membrane of those cavities, the internal skin 

 or mucous membrane, and is composed essentially of two layers, 

 dermis and epidermis. 



The DERMIS or cutis is chiefly composed of areolar tissue, besides 

 which it has entering into its structure elastic and contractile fibrous 

 tissue, together with blood-vessels, lymphatic vessels and nerves. 

 The areolar tissue exists in greatest abundance in the deeper stratum 

 of the dermis, which is consequently dense, white, and coarse ; the 

 superficial stratum, on the other hand, is fine in texture, reddish in 

 colour, soft, raised into minute papillae, and highly vascular and sensi- 

 tive. These differences in structure have given rise to a division 

 of the dermis into the deep stratum, or corium, and the superficial, or 

 papillary layer. 



In the Corium the areolar tissue is collected into fasciculi, which 

 are small, and closely interwoven in the superficial strata, large and 

 coarse in the deep strata ; in the latter forming an areolar network 

 with large areolas, which are occupied by adipose tissue. These 

 areolae are the channels by which the branches of vessels and nerves 

 find a safe passage to the papillary layer, in which and in the superficial 

 strata of the corium they are principally distributed. The yellow 

 elastic tissue is found chiefly in the superficial strata, the red con- 

 tractile tissue in the deep. It is to the latter that the nipples and 

 scrotum owe their contractile powers, and the general surface of the 

 skin the contraction which is known by the name of cutis anserina. 

 The corium presents some variety in thickness in different parts of the 

 body. Thus in the more exposed regions, as the back, the outer 

 sides of the limbs, the palms and the soles, it is remarkable for its 

 thickness ; while on protected parts it is comparatively thin. On the 



the anatomy of the various glands : his work, intitled " Adenographia," &c. was 

 published in 1656. 



* Nicholas Stenon, a Danish anatomist : he was made professor in Copen- 

 hagen in 1672. 



