34 PHYSIOLOGY. 



21. The next layer of the skin is the fate mucosum, or 

 mucous web.) It has been supposed to consist chiefly of 

 mucus, as it is of a soft pulpy texture. It is the/seat of the 

 coloring matter in the different races$ In the European, it 

 is white, in the African black, and in the Mulatto and Malay, 

 copper-coloured. In the Ethiopian race, it is much thicker 

 than in the light-coloured varieties of the human species, and 

 may easily be separated both from the cutis and cuticle, and 

 made to appear as a distinct membrane. 



22. The dark color of the skin in the inhabitants of the 

 torrid zone, is ascribed by most physiologists, to the influence 

 of the sun upon the surface of the body ; but the tinge pro- 

 duced on the skin by exposure to a bright light, appears 

 to have no connection with the permanent colour of the 

 negro. Dr. Bostock states, that the blackest complexions 

 are not found in the hottest regions, and that there are 

 some tribes nearly under the equator, whose skin is 

 whiter than that of many Europeans. Besides, the tinge 

 produced by the sun is not transmitted from parents to 

 their offspring, whereas the children of negroes are equally 

 black in whatever climate they are born, and their com- 

 plexion is not altered by any number of generations. When 

 a person is tanned, as it is called, by the influence of the 

 sun, it is the cuticle only which is affected ; if this be 

 removed by a blister, in a few days new cuticle will be 

 formed, and the skin in that place will appear as white as it 

 ever did. 



23. Albinos. In the Caucasian race, from which Europe- 

 ans and Americans have descended, there is usually a mix- 

 ture of red or brown, with white in the complexion ; but 

 where the skin is of a uniform, clear, pearly whiteness, the 

 individuals are called Albinos, from albus, white. In these 

 persons, the hair is generally white, corresponding with the 

 colour of the skin, while the eye is without that substance 

 which gives the various colours to the iris. The iris, in such 



