INTEGUMENTS. 



matter. I think we fliould underfland, by the reticular 

 body, an inter-texture of extremely line veflels, the trunks 

 of which, already very rtvinute, after palling through the 

 numerous perforations of the corion, are ramified on its fur- 

 face, and contain different kinds of. fluids. The exiitcnce of 

 this vafcular net-work is placed out of all doubt by 



called tanning : this alteration is %'^ry rapidly produced hf^ 

 jToing much on the watery in confequence of the refleftion ot 

 the light from its furface. That tliis is the confequeiTce of 

 the caufe jull afligncd, and that the effcft is not produced by 

 heat, is rendered obvious by the difference of colour in the 

 face and hands, and on thofe parts of the body which are 



injeftjons, which, entirely change the colour of the'dvin on habitually covered : alfo by the brown tint of the face pro 



the outfide, without altering it much internally. This 

 the principal feat of the various eruptive diforders, moil of 

 which are altogether foreign to the corion. 



" We may then conceive the reticular body as a general ca- 

 pillary fyftein, furrounding the cutaneous organ, and form- 

 ing, with the papillse, a ilratum intermediate to the corion 

 and epidermis. In the white part of the human race this 

 fyftem contains only white fluids ; in ihe negro they are 

 black, and of various tints in the other varieties of our fpe- 

 cies. The enumeration of the different fliades of this organ, 

 and the confideration ot the caufes of thefe varieties, belong 

 to the natural hillory of man Hitherto we have very few 

 data concerning this fubllance : it docs not fecm to circulate 

 in the part. We fee that llie negro's fl<in is black, and we 

 know very little more, 'i'lie rete fonietimcs adheres to 

 the cutis, but generally to the cuticle, when they are fepa- 

 rated after maceration. It is manifellly foreign to both, 

 fince they have tlie fame colour in the dark as the white 

 races.'' 



duccd by a fummer's fun, which offers a remarkable contralt 

 to that of the forehead, where it is protedted by the hat. 

 Our clothes do not prevent the attion of heat upon the fl<in, 

 but will intercept the luminous ;-ays. The pale and fallow 

 tints of the inhabitants of large towns, compared to the 

 florid countenances ot country people, aritc from the fame 

 caufe. Men are blanched like plants wheii flnit out from 

 the influence of the fun. Tanning takes place much more 

 quickly in individuals of light complexion, than in thofe of 

 an oppofite tharadter. The effeft in all cafes is temporary, 

 and goes off when the caufe no longer afts. It is produced 

 in a greater and more jx^rmanent degree in white hidividuals 

 who move into warm climates: but neither here nor in any- 

 other inllance is it trani'mitted to the offspring. Phyfiolo- 

 gidshavc chofen toreprefent this as a change occurring in 

 the retc nuicofum ; on what authority we do not know. 

 The light brown fpots, called freck'es, which occur about 

 the head and neck %vhen expofed to fun and air, feem to be 

 of the fame nature with the tanning. The colours iniprefled 



It feems really to be a matter of doubt, whether in the on the Ikin in the operation of tattowing, refide in the cutis, 



white races there be any colouring-matter in the exterior and confequently remain when the cuticle and rete mucofum 



capillary fyftem analogous to the black fubllance of the have been dellioyed by maceration. Thefe colours are per- ■ 



negro, or whether the colour of their furface firife merely manent : they remain through life, and the marks can only 



from that of the cutis and cuticle. Tha-t there is fome co- be deftroyed by removing the fliin which contains them ; a 



louring-matter is rendered probable by the fingular anomaly circumftance which is hardly reconcileable to our notions of 



exhibited in the albinos; which fee. Wt can demonftrate in the conftant changes of decompolition and compofition in 



that cafe the abfence of the pigmentum nigrum of the eye, all parts of I he frame. 



and we fee clearly the deficiency of colour in the hair. The Mr. Cruikfliank defcribes a vafcular membrane as exifting' 



peculiar dead white of the Ikin is referred, by analogy, to the between the rete mucofum and cutis ^ and apparently it is 



want of the colouring principle in that organ. There is the fame as the vafcular net-work of Bichat. He injefted 



generally a conneftion between tiie colour of the flcin, hair, this in the flvin of perfons who had died of fmall-pox ; and 



and eyes, which is remarkably evinced in this inftance. A was led to inveftigate the matter from s converfation with a 

 dark complexion is accompanied with black hair and tlark • gentleman who conceived that he had injefted veiTels in the 



eyes ; and the light irides, as the blue and grey, occur in in- rete mucofum. He macerated in putrid water, during the 



dividuals with red, flaxen, or other hght fliades of the hair fummer, portions of fmall-pox fl-;in, which had been kept for 



and light (km. All thefe circumllances lead us to conclude fome time in fpirits. " Cuticle and rete mucofum were al-- 



that the Ikin, hair, and eyes have their colour dependent on ready turned down ; and upon the eighth or ninth day I 



fome peculiar matter, the tint of which follows a general found I could now feparate a vafcuiai- membrane from the- 

 law in all thefe parts. 



Even in the white races certain portions of the flvin fome-: 

 times exhibit a dark colour. The areola round the nipple 

 becomes black or dark brown in women who are fomewhat 

 advanced in pregnancy, and affords a very fure maik that 

 they are pregnant. Haller fays that he faw the flvin of the 



cutis, in which were alfo fituated the injeited fmall-pox piif- 

 tnles. Thefe laft contiiled of circles of long-floating villi- 

 at the circumference, but of a white uninjecled lubffance in 

 the centre* This central part Mr. Hunter had pievioufly 

 faid was a flough formed by the irritation of the variolous 

 matter. The furface of the ftin, from whence this mem- 

 pubes in a woman approaching nearly to that of tlie negro brane was fepar.ited, was elegantly porous. The pores novv* 

 in blacknefs ; and Albinus mentions a iimilar circumftance appeared exceedingly more numerous, and this furface of the 

 in a man. (kin was ftill tough and fliining. I macerated the fame fkin 



The colour of the fltin is tranfmitted to the offspring, and for four or five day 

 is furprifingly altered by intermarriages of the different 

 races. Where a black and a white individual copulate, the 

 offspring has the middle tint between thofe of its parents. 

 If the child of a black man fliould intermarry with a white 

 pcrfon, and their child with another white individual, and 

 fo on, the offspring will be white in the fourth generation ; 

 or -vice -vtrfa. But the detailed confideration of this fubjeCl 

 belongs, more properly, to natural hittory 



nd fepai-ated ; 



embrane. 



more delicate than the former, but alfo vafcular. The for- 

 mer I eafily preferved ; the latter, attrafied by the inftru- 

 nient that feparated it, or unable to bear the agitation of the 

 water or fpirits in which it was feparated, conftantly broke 

 down. But tile eonefponding furface of the fl<in was ftill 

 tough and fliining ; the pores were now much larger and 

 more diflincl than before, and convinced me that the appear* 

 ance was natural, and that the fltin had fullaincd no real in- 



The colour of the cutaneous organ in the white races of jury in the procefs." Experiments on tlie infenfible Perfpi- 



the human fpecics is much modified by accidental circum- ration of the Human Body, &c. p. ^S. 



ftances. Expofure to the funs rays produces various It has generally been ftated that the rete mucofum is not 



fliades of a reddifli-brown colour, which effecl is commonly regenerated when it has been deftroyed in ulcers j and confe- 



. . 5 qucntly 



