334 INTEGUMENTS. 



tebrated animals; and are now generally acknowledged by the 

 French anatomists. In negroes, in cutting through the skin of 

 the sole of the foot, from heel to toe perpendicularly to the fur- 

 rows, this arrangement is readily recognised;* and when it has 

 become indistinct, it may be improved by immersing the skin 

 for three or four days in lime-water, or a solution of potash or 

 barytes, and afterwards keeping it the same length of time in a 

 solution of corrosive sublimate. Blisters also elucidate this 

 point on other parts of the body: the fluids being locally at- 

 tracted there, infiltrate the rete mucosum, and separate in part 

 its 'layers, so as to form a vesicle frequently very thick, parti- 

 cularly in fat persons. 



The scrotum of the negro is also well suited to the exhibition 

 of the rete mucosum, as it is there very distinct, and is univer- 

 sally much thicker and better marked in the negro than in any 

 other race. From its extreme tenuity in the whites its existence 

 in them has by some persons been doubted, but erroneously, as 

 in them also its change of colour, from the influence of the sun, 

 is readily demonstrated. There are in fact few persons, perhaps 

 none, so white, but what a slight tinge of yellow exists in their 

 skins; which may be proved by contrasting them with any per- 

 fectly white surface, as snow, bleached paper, or linen. This 

 slight tinge of yellow is increased to an olive colour by the sun's 

 rays, and, in some instances by a spontaneous deposite; in other 

 cases, it is in certain spots removed, so as to leave a colour al- 

 most perfectly white, or that only of the cutis vera.t When the 

 latter change occurs in the African, it occasions a hideous pie- 

 bald complexion, and the cuticle is readily elevated into blisters, 

 by the irritation of the solar rays. Some persons have an entire 

 deficiency of this pigment on the skin, from birth; the same de- 

 ficiency occurs in the eyes, and hair; they are designated as al- 

 binos. The deficiency of the pigmentum nigrum in the eye, 

 causes it to look red, like that of the white rabbit; and also 

 makes it intolerant of a strong light, as that of noon-day. 



" In some very remarkable instances the skin becomes entire- 

 ly black. We have read to the Society of Medicine of the Fa- 



* J. Cloquet, Anat. De L'Homme. PI. cxvi. Fig. 6. 



f A case of this kind is now in the Philadelphia Alms House, where the ab- 

 sorption of colour has occurred in spots on the hands of a dark-complexioned Eu- 

 ropean. June 15, 



