ANIMAL OKGANIZATION. 99 



surfaces, thus furnishing them with a protecting 

 investing membrane, constitutes a thin layer of a 

 soft gelatinous consistence, intermixed with minute 

 scales ; these scales are coloured by a material 

 termed the pigmentum, from which the skin derives 

 its peculiar hue.* 



The corpus mucosum is covered externally by 

 the epidermis, into which it is itself gradually con- 

 verted, in proportion as the latter is, in process of 

 time, worn away ; its place being supplied by a 

 fresh production of the same material. For this 

 purpose a secreting apparatus is provided, consist- 

 ing of a vast number of minute glands, termed by 

 Breschetl the hlennogenous glands, which, are lodged 

 in the deepest part of the corium. The albuminous 

 matter which they prepare is conveyed by ducts, 

 one proceeding from each gland, which traverse 

 the whole thickness of the corium, till they reach 

 its outer surface, when they open at the bottom of 

 the furrows, between the rows of papillae. Here 

 also terminate another set of canals, much shorter 

 than the former, inasmuch as they proceed from 

 organs situated immediately below the corpus pa- 

 pillare, and consequently close to the outer surface 

 of the corium. These latter organs, which are also 

 of a glandular nature, are denominated by Breschet 

 the clu'omatogeuuus glands, because they prepare 

 the pigment already spoken of, as mixing itself 

 with the albuminous fluid to form together the 

 corpus mucosum.]; 



* Being black in the Negro race, it was termed by Malpighi, its 

 discoverer, the Pir/mentum nigrum. 



t Nouvelles Recherches sur la structure de la Peau. Paris, 183,5. 

 t On raising the epidermis from the corium, a portion of the layer 



