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On the Functtotis of the Colouring Matter of the Skin in the 

 Dark Baces of Mankind, By Robert Mortimer Glover, 

 M.D., Lecturer on Chemistry in the Newcastle-on-Tyno 

 School of Medicine. (Read to the British Association at 

 the Newcastle Meeting.) Communicated by the Author. 



Various hints and hypotheses have been put forth as to the 

 functions performed by the peculiar organization of the skin 

 in the dark races of mankind. The opinions of Sir Everard 

 Home, published in the Philosophical Transactions for 1821, 

 have been generally adopted by physiologists as apparently 

 founded on a methodical attempt to investigate the subject by 

 direct experiment, and to elucidate it by analogical reasoning. 

 The experiments of Sir Everard give results certainly quite 

 opposed to what has been determined by physical observers 

 respecting the laws which aifect the radiation from, and ab- 

 sorption of, heat by coloured surfaces. This circumstance 

 drew my attention to the subject, and led me to repeat some 

 of the experiments related by Sir Everard. 



It may be mentioned, before entering on the subject, that 

 this inquiry was proposed by Lord Bacon. 



The structure of the skin and of its layers is yet involved 

 in some doubt as to many particulars ; but so far as our in- 

 quiry is concerned there is no doubt whatever. It is clear 

 that there is a spongy or vascular layer between the cuticle 

 and true skin ; or on the surface of the latter, constituting a 

 portion of it. It is also certain that the colouring matter of 

 the skin resides in this region. And that the intensity of 

 shade is the greater or less abundance of the colouring matter. 

 Hence the European and the Negro furnish extreme instances 

 in this inquiry ; since in the one the colouring matter is in 

 small quantity or of light shade, whereas the other has it so 

 abundantly that in him we speak of the pigmentum nigrum. 

 Between these extremes exi-^t many curious varieties, in whom 

 the functions of the colouring matter are well worthy of con- 

 sideration, but we have data to reason only with regard to the 

 European or White, and the Negro. Indeed, in many of the 

 coloured races, the existence of something analogous to the 



