INTEGUMENTS. 



rouglincfs and harflinefs of tlic (kin ; it might lead us to fup- 

 pofc that the epidermis forms them, although it is only ac- 

 ceffary. Where the latter is thick, as in the palms and 

 foles, thcfe cutaneous tubercles are never feen." 



The proper papillsc of the fkin are very vifihle in the 

 hands and feet, and may be feen when the cuticle has been 

 carefully removed after fimple maceration for a fufficient 

 time; but ftill more plainly when the cutis has been minutely 

 injeAed previous to the macerating procefs. We obferve 

 narrow, longitudinal, and flightly prominent lines in the 

 cutis, diilributed fpirally at the ends of the fingers and toes. 

 From thefe ridges arife very fmall conical procelTis like fine 

 threads or hairs, (lightly inclined towards the nail, (horter 

 and more impcrfeft in the fmailer toes and fingers ; they give 

 a rough villous appearance to the furface, which is repre- 

 fented in the feventh figure of Mr. Cruikihank's work on the 

 infenfible pcrfpiration. They are very diftinft in the red 

 part of the lij ?, where they are numerous and long, and pro- 

 duce a villous appearance ; Ruyfch has figured them in his 

 eighth Thefaurus. The foft and fpongy fkin of the glans 

 penis is remarkable for a fimilar ilruAure, which is veil 

 reprefcnted by Albinus in the Annot. Acad lib.iii. tab. 4. 

 They are more obtufe in the female niamms. The minute- 

 nefs of thefe organs renders it difficult to afcertain their in- 

 ternal ftrufture fatisfaftorily. They receive numerous blood- 

 velfels, fo as to become much more deeply tinged by 

 coloured injections than the furrounding Ikin. They receive 

 numerous nerves, and have generally been regarded by ana- 

 tomiils in a particular manner as organs of a nervous llruc- 

 ture. That a confiderable fupply of nerves is bellowed on 

 ihofe parts of the ikin which have thefe papilli is very 

 clear ; but, that the minute filaments can be traced into the 

 very prominences, and that they lay afide their ceverings, fo 

 that the nervous pulp is bare in them, muft be regarded as 

 inferences from analogy rather than from direft obferv;ition 

 The denfity of the corion, and. the extreme flendernefs of 

 the nervous threads, are alraoft infuperable obftacles to our 

 tracing the nerves into the papillas. 



We can fcarcely doubt, fays Haller, that thefe bodies are 

 the organs of touch, when we obferve them larger, more 

 diilinft, and receiving a greater fupply of nerves where this 

 fenfe exifts in the n:oft acute degree, hardly difcernibie in 

 other fituations ; and particularly ca'culated by their pro- 

 minence to be imprefled by external objects. Perhaps their 

 exiftence in the fole of the foot, where they are covered by 

 fo thick a cuticle, is hardly reconcilcable with this opinion. 



That the vefTels, which they contain, contribute to the 

 fcparation of the matter of perfpiration, is fo conformable 

 to general analogy, that we can cailly admit it. Mr. Cruik- 

 fhank was difpofed to regard them as the organs of cutaneous 

 abforption from their rcfemblance to the inteflinal villi, on 

 vhich he difcovered the orifices of the lafteals. 



EffeS of iiarious Agents on the Dermoid TiJJue We have 



noticed already, under the head of the rete mueofum, the 

 aftion of light upon the living fl<in. 



The aftion of caloric on the living integuments prefents 

 different phenomena, according to the degree in which it is 

 applied. A warm atmofpliere relaxes its tiflue, increafes 

 its aftion, and promotes the evacuation by the exhalants of 

 the refidual fluid of nutrition and digcftion. It is coutraftcd 

 and corrugated by cold, and refufes to admit thefe fluids, 

 which then go off chiefly bv urine. The gradual change 

 from one to the other of thefe llatcs does not produce any 

 unpleafant effcft : but fudden viciflitudes are not fo free 

 from danger. Tlie cold produced by the evaporation of the 

 cutaneous exhalation, enables the human fubjcft to prelVrvc 

 kis crdinary temperature in air, heated above the degree of 



boiling water. See the very curious fafts en this fubjeft 

 detailed in the article Heat, Animal. The interruption of 

 the cutaneous difcharge on the corrugation produced by cold 

 fufpends this evaporation, and thereby prevents the tempera- 

 ture from being lowered beyond the nat\iral ftandard. 



When more confiderable heat is applied to the fl<in, it 

 produces firll a fenfible rcdnefs, which fs followed by vefi- 

 cations. If it be increafed in degree, tlie texture of the 

 organ is deltroyed ; it is hardened and curled up, like any 

 other animal tiflue when burnt ; beyond this point it is 

 blackened and converted into a coal. Tlie firft operation is 

 on the vital powers of the organ, and confequently can take 

 place only during life : the latter effefts are produced on the 

 tiflue, and may be exhibited in dead flcin. The latter, when 

 heated, contrafts, and then fwells, exhales a fetid odour, 

 and leaves a denfe charcoal, d fficult to incinerate. On 

 diilillation it yields the fameprodufts as fibrir.e. Intenfe cold 

 produces in the firft place a rednefs of the organ, as in the 

 nofe, ears, fingers, &c. of individuals expofed in a ver)- cold 

 climate ; inflammatory aftion and mortification enfue. The 

 latter occurs immediately on the application of high tem- 

 perature, but after fome interval in the oppofite cafe. 



The air evaporates and carries off habitually the matters 

 fecreted from the flvin : and when this efi^eft is not produced^ 

 they ai-e accumulated on the furface, and render it moiit. 

 This evaporation is a phyfical phenomenon entirely diftinft 

 from the vital aftion of tranfpiration. The latter takes 

 place in a warm bath, as well as in the air ; but in the 

 former cafe the fluid is difiolved by the water. Does free 

 expofure of the fivin to air ircreafe or diminiih the amount 

 of its exlialation ? The common opinion feems to be that the 

 latter effeft is produced ; the exhaling pores are fuppofed to 

 be obflrufted by the impreffion of cold on the ikin. Dr. 

 Stark, however, proved by direft experiment in his own per- 

 fon, that the body loft more weight in a given time "when 

 naked, than when covered by the ordinary clothing. 



Moifture of the fliin may be produced in two perfeftly 

 diftinft ways; ift, by increafed exhalation, which may arife 

 from accelerated aftion of tlie heart, as in violent exercife or 

 fever ; from relaxation of the organ by the warmth of the 

 air, or by baths; or from fympathy, as in confumption, fear, 

 &c. Under all thefe circumftances the increafed difcharge 

 will keep the fl<in moift. 2dly. The fame efleft will be pro- 

 duced by inlufficieiit diflblution of the perfpiration when it 

 is produced, as in bed, or in damp weather. 



When the air has aceefs to dead flcin on all fides, it is 

 dried, and becomes tranfparcnt, unlefs it Ihoiild contain 

 blood ; it is then firm, but admits of being bent. In this 

 ftate it yields very little to external agents, does not readily 

 abforb moifture, and has no difagreeable fmell. Hence flcins 

 fimply dried are of great ufc in the arts, and afford fervice- 

 ahle and plcafant coverings ; hence, too, probably the great 

 durability of the mummie?. 



If the fl<in be left on the body, or expofed in moift air, 

 it putrefies, afTuining fucceffivtly a brown, a greeiiifh, and 

 lalily fomouhat black colour. It exhales a molt fc'.id odour, 

 and becomes fwollen by the liberation of gas. A fluid mucus 

 appears on its furface, from which the epidermis is then fe- 

 parated. When all the fluids are evaporated, a blackifh 

 iubllance remains. 



Water removes from the living fkin thofe parts of the 

 perfpired matter which are not difiolved by the air ; and the 

 ufe of bathint', which is much neglected in thefe di.ys, muft 

 be regarded as an efficacious means of prelerving the furface 

 free from acrid and irritating matters, and confequently in a 

 llate of health. We cannot ftate precifely what aftion baths 

 have on the hving fiiin ; we arc told indeed that they relax 



and 



