224 GENERAL ANATOMY. 



322. The skin sometimes presents primitive vices of con- 

 formation, either by deficiency, which causes divisions or de- 

 nudations in the foetus, or by excess, which forms folds or sacs 

 more or less extensive. It presents also acquired vices of con- 

 formation; its distention, carried to a great degree, as for in- 

 stance in pregnancy, separates, loosens the fibres of the dermis, 

 and produces welts, after delivery, which at first are brown or 

 blackish, that afterwards become and remain more white and 

 shining than the rest of the skin. A more moderate and more 

 continued degree of distention, produces a loss of its elasticity 

 and retractility, and when it is removed leaves wrinkles more 

 or less deep. 



323. The skin is the frequent seat of congestions, dis- 

 charges, and inflammations, acute and chronic, whose various 

 effects, either on the texture of the membrane, on its colour, or 

 on the products of its secretion, have given rise to the esta- 

 blishment of fifty genera, and more than a hundred species of 

 cutaneous diseases, consisting of pimples, scales, eruptions, 

 ampullae, pustules, vesicles, tubercles, spots, &c., respecting 

 which the works of Plenck, Alibert, Willan, and Bateman, 

 may be consulted with advantage. 



324. The retention of the sebaceous matter, and its accu- 

 mulation in the follicles, give rise to the formation of tumours 

 called pimples, when they are small, and which, when large, 

 are confounded with the encysted tumours under the names 

 of wens, meliceris, steatomatous tumours, and atheromse. 

 When the tumour is small, and the orifice of the follicle is not 

 obliterated, the sebaceous matter may be forced out of it by 

 pressure in the form of a worm, a circumstance, which has led 

 some inattentive observers, who are fond of the marvellous, 

 into error. When, on the contrary, the tumour has greatly in- 

 creased, and grown voluminous under the skin, and its orifice 

 is not apparent, it greatly resembles a cyst; but by dissecting 

 it with care, traces of the orifice may be found in the point 

 where it holds to the skin; and if we split the skin and the tu- 

 mour in that point, we can easily follow the epidermis, which 

 is reflected from the surface of the first into the cavity of the 

 second. Whether the matter contained in it, resemble honey, 



