INTEGUMENTS. 



Bne^iglith of an inch. Tliefe may be vefibls ; but it is c!e, and throws it into numerous wrinkles. This effeft is ob. 

 only a_ conjecture. On examimr.g the furfact of the fe- f^^rved in the application of poultices, and feems to arife from 

 paralea cuticle, numerous prolongations of various lengths the tiflue becoming penetrated with the fluid • it takes place 

 are obferved, appearing like f.miU ends of fine threads, or to the gicatelt degree in the foot and ha.d, and often is hard- 

 as mere mequahties, and dilpoled obliquely. Thcfe may ly fenfib'e in other parts. The fenfibility of the Ikin is ren 

 be abforbents and cxhalants. Whatever the medium of dercd more obtufe by this change in the cuticle The water 

 conncaion may be, the adhehon of the parts to each other imbibed by the part is'ifterwards evaporated, the wrinHes 

 is very ftrong. „ r r d'fappear, and the cuticle recovers its former Rate. When fe- 



Various caufes deitroy this adhcfion of the epidermis, and parntcd from the body, and immerfed in water, it is whitened : 

 occafion its reparation. Ac.ite inflammations, as eryfipelas, it undergoes no putrid alteration, but is covered by a whitifti 

 phlegmon, &c. are followed by its detachment; and various pellicle formed gf feparate molecuht. At the end of two 

 eruptions, not of an inflammatory nature, caufe its detach- or three months it is foftened, and may be torn very cafily, 

 ment in a dry fcaly form ; which hasgivten rife to the notion but does not fwell : it is never reduced to a pulp analogous 

 thatitismadeupoffcales in its. natural Hate. When the fldn to that of other organs when macerated. I'.oiliiig never 

 is unequal on the fiirface, friftion detaches it in fmall fcales, produces crifpation or csrrugation of this lifl'ue : prolonged 

 which give a very rough appearance to the part. Fevers are ebullition renders it kfs reliiiant, fo that it may be torn viry 

 not unfrcquently followed by defquamation of flcin. The eafily, but never reduces it to gelatine, nor gives it a'yellow 

 adion of veficatones is famiUarly known. In the dead fub- colour. The laminx which compofe it in the hands and feet 

 ject, putrefaction, maceration, and ebullition are the molt are eafily feparated after long boiling. Tlie tanning principle 

 eifedlual means of accomphfliing the feparation. has no adtion on it ; nor has alcohol. 



The thicknefs of the epidermis is in genera! very uniform : When well dried in the air, .and expofcd. to the flame of 

 it does not feem to follow thofe varieties which we obferve a candle, it undergoes no crifpation, as a piece of fl<in does 

 in the cutis of the trunk, limbs, &c. It is only in the when treated in the fame way : it exhales a fetid odour analo- 

 palms and foles, and on the correfpondin^r furfaces of the gousto that of burnt horn. It burns with oreatfacilitv.fothat 

 fingers and toes, that its thicknefs is increafed : and here the if it be lighted at one end, it will often bc^eii tircly confumed. 

 augmentation is fo confider.ible, that there is no proportion A blackidi fluid is obferved ifi the flame, li.ke that of burnt 

 between thefe and other parts of the body. . feathers. This is clearly of an oilv nature, keeps up the 



There feem to be in this part feveral additional lamina: ; combuRion by its great abundance, and is found in fo large 

 and the inner furface, after feparation, does not exhibit a quantity only in the hair and nails : this produces a dff- 

 thofe proceflbs already fpoken of. This exceffive thicknefs agreeable odour. A blackifli coal remains after combuftioni 

 prevents the action of blulers. In repeated trials Bichat Light does not feem to atTeft the epidermis, which is not 

 found that they prod-xed no effea. The tranfparence of changed when expofure to the fun has altered the appearance 

 the epidermis is deftroyed by this thicknefs : it is here of the {l<in. 



whitilh, and even opaque. Hence, in the negro, it conceals Nitric acid turns it yellow, but diflblves it witb great diffi. 

 the black colour of the reticular body ; which, however, is, cuky. Sulphuric, on the contrary, when not rmich diluted, 

 at the fame time, lefs black hefe than in other parts, ads very powerfully on it, rendering it very thin and tranf! 

 The epidermis in thefc fituations is manifettly compoled of parent, or diflblving it entirely by long immcrfion. Alkaline 

 fucceffive lamina, adhering with fuch f^rce, as to be very folutions diflblve it, but with difficuhy°: pure alkali adls on it 

 difficultly feparated : in all other parts we can difcern only a rapidly; as alfo does lime, according to Chaptal. 

 fimple layer. No fluid can be noticed in this tiffue : when cut If, fays Dr. Thomfon, the cuticle be tinged with nitric 

 ki various direftions, either in the living or dead fubjea, acid, the application of ammonia to it is well-known to give 

 nothing exudes. Its fcales are always perfeftly dry : iJie it inllantaneoufly a deep orange colour. Nov/, as Hatchett 

 a^bforbents and exhalants merely traverfe it. No biood in has fhewn that this change is alfo produced upon coagulated 

 the living ftate, nor injeftion after death, enter it in any cafe, albumen in the fame circumftances, and as the epidermis re- 

 It never participates in the difeafes of the fubjacent organ, fembles that fubftance in all the properties above detailed, it 

 except by being elevated when that is fwollen, and then de- can fcarcely be doubted that it is any thing eifc than a pecu- 

 tached. Nerves and cellular tilTue are completely foreign to liar modification of coagulated albumen. Syll. of Che - 

 it. Thus we fee that none of the general fyllems, common miftry, v. 5, p. 574. 



to all organs, enter into the compofition of the epidermis : ProperlUs.— It has very little extenfibility, as the fmalleft 



it has not the common bafis of all organized parts ; and in cutaneous tumour caufes' it to crack, and be detached in 

 this point of view m.ay be regarded as inorganic. It feems fcales. Yet it is not entirely deftitute of this property, as 

 to contain no fibre in its compofition : it poflefltis very little its elevation in bliilers proves. It has no contraftihty r 

 power of refinance, breaking under a flight diftention, ex- when no longer diftended, the portion elevated in a blifter 

 cept in the foles and palms, &c. where it is fo thick. Cvllapfcs in wrinkles, andi'does net regain its original fize. 



The aftion of air produces hardly any effeft on it. When It has no animal fenfibility in any part : it may be ; ricked,' 

 a large piece is expofed, it becomes rather harder, and more cut, torn, or injured in all parts 'without exciting any fenfa- 

 con.'illent, and is torn more difficultly. Next to the hair tion. It differs from other organs, as cartilages, tendons, &c. 

 and nails, it is the tiffue lead changed by deficcation. It is ren- which alfo have no animal fenfibility, in being aUogether unl 

 dered a little more tranfparent, but iminerfion in water reftores fufceptible of that property, which they often acquire under 

 if to its former ftate. When the fl<in piffes into a Itate of pu- certain kinds of excitement. The epidemiis is equally def- 

 trefaaion, thecuticleisnotatallchanged. It is feparated from tituteof the organic fenfibility, and organic infenfible con- 

 the cutis, but not rendered at all putrid ; if it be thoroughly tradility : it poflcffes no circulation, and is fufceptible of no 

 walked, it has no bad odour. AVhen prcferved in moift air, difeafes, which depend on the organic properties. We have no 

 it is not chanjj-ed ; and it may be regarded as the moll in- proof, in fnort, that it enjoys any vital powers at ail; fo that 

 corruptible ot animal fubllances, after the hair and nails. wcmayco-.ifider the whole fupeiticics of the body as c'ompofed 

 • Moillure applied for a long time whitens the living cuti- of dead matter. " Its life," fays Bichat, " is extremely ob- 

 3 \ ' Iturc I 



