ANATOMY. 



the ends of the fingers as more particu- 

 larly adapted, by their organization, for 

 exploring the tangible properties of bo- 

 dies. 



The skin, or exterior covering of the bo- 

 dy, is divided into three layers, viz. the 

 cuticle, the rete mucosum, and the cutis. 

 These parts are called the common inte- 

 guments of the body. To them a fourth 

 is sometimes added, v'z. the adipous 

 membrane. But although there is gene- 

 rally a layer of fat under the skin, this is 

 not invariably the case. 



The cutis vera, or true skin, is a very 

 dense and compact membrane, formed, 

 as it: were, by a general condensation of 

 the cellular substance on the surface of 

 the body. It is this that forms leather, 

 when subjected to the operation of tan- 

 ning. Its thickness varies in different 

 parts of the body. It possesses consider- 

 able elasticity, by virtue or which it yields 

 to any distending power, and on the cessa- 

 tion of such force recovers its former 

 state. It has also a species of contracti- 

 lity, which is evinced by its corrugation 

 from cold. Its colour in the inhabitants 

 of all countries is white. It possesses 

 great vascularity, and has also an abundant 

 supply of nerves, which bestow on it 

 acute sensibility. It is thrown into 

 folds in different parts of the body, in 

 consequence of their motions on each 

 other ; this may be particularly observed 

 in the hands and fingers. Its surface is 

 also marked by lines, crossing and inter- 

 secting each other variously, and inter- 

 cepting spaces of all shapes and descrip- 

 tions. 



Such parts of the cutis as are the most 

 highly organized have numerous fine 

 hair-like processes, called villi. These 

 are more vascular than other parts, and 

 receive also a more copious supply of 

 nerves. Such parto enjoy a higher and 

 more acute sensibility. This is the case 

 with the ends of the fingers, which, both 

 by their form and organization, are more 

 especially fitted to act as organs of touch. 

 It is also observed in the lips^ and in the 

 g-lans penis. 



The rete mucosum is a soft mucous 

 substance, readily demonstrable in the 

 negro, where it is thick and of a black co- 

 lour, but hardly discernible in the Euro- 

 pean. This is the seat of the colouring 

 matter of the skin. 



The cuticle is a thin semi-transparent 

 covering, possessing no particular arrange- 

 ment of parts, no vessels nor nerves. It 

 adheres, however, closely to the subjacent 

 jiarts, and is exactly moulded to the sur- 



face of the cutis. It is best seen after 

 the action of a blister, when it is elevated 

 by an effusion of fluid under it. In the 

 dead body it may be separated from the 

 cutis by putrefaction, or by immersion in 

 hot water. In this way it may be remov- 

 ed, entire, from the hand and fingers, so 

 as to resemble a glove 



It forms an insensible medium, interpos- 

 ed between the nerves of the organ of 

 touch and external objects ; and as it co- 

 vers the whole exterior of the body, our 

 surface is actually dead. When removed 

 from any part, it is speedily renewed by 

 the cutis. Its thickness varies in different 

 parts; being greatest where it is exposed 

 to friction, as in the palms and soles. Its 

 thickness is here also increased by fric- 

 tion, as we may observe, by contrasting 

 the hand of a labourer with that of a per- 

 son who does not use his hands in the 

 same rough manner. 



It appears that the cuticle is impervious 

 to fluids, as the. sc mm contained in a blis- 

 tered part does not transude; neither does 

 a dead body become dried while covered 

 by this expansion; but when that is re- 

 moved, it is speedily reduced by evapora- 

 tion to a state of dryness. Yet it must be 

 penetrated by the vessels in a living body, 

 as is proved by the immense discharge 

 botii of sensible and insensible perspira- 

 tion. Probably, also, the absorbents open 

 on it by natulous orifices; for mercurial 

 ointment/rubbed on the skin, affects the 

 system. 



Sebaceoics glands are formed under the 

 'skin, in a few situations only, as about the 

 nose and external ear. 



Hairs consist of an insensible excre- 

 scence produced from the cutis. Each 

 hair grows from a small bulb, and is 

 lengthened by means of additions made 

 to it in the bulb. These bodies perforate 

 the cuticle. 



JVcwVs are portions of a horny substance, 

 connected to the ends of the toes and fin- 

 gers. Their surface, corresponding l.o the 

 back of the finger, is convex, and tolera- 

 bly smooth ; the opposite part is laminated 

 and concave. These laminae adhere to 

 corresponding ones of the cutis. The in- 

 teguments advance for some length over 

 the root of the nail, so as to, cover a con- 

 siderable portion of it ; and the cuticle 

 adheres closely to its surface. The nail 

 grows like the hair, by additions from 

 below. 



The account of the progress of the em- 

 bvyo after conception, or the description 

 of the gravid uterus and its contents, toge- 

 ther with the enumeration of those circum- 



