ORGANS OF TOUCH. 



123 



the secretion of this mucous matter, composed of a glandular paren- 

 chyma or organ of secretion situate in the substance of the derma, and 



Fig. 38. 



Fig. 39. 



Vertical Section of Epidermis, from 

 Palm of the Hand. 



a. Outer portion, composed of flattened 

 scales, b. Inner portion, consisting of 

 nucleated cells, c. Tortuous perspiratory 

 tube, cut across by the section higher up. 

 Magnified 155 diameters. 



Surface of the Skin of the Palm, 

 showing the Ridges, Furrows, 

 Cross-grooves, and Orifices of the 

 Sweat-ducts. 



The scaly texture of the cuticle is 

 indicated by the irregular lines on the 

 surface. Magnified 20 diameters. 



of excretory ducts, which issue from the organ, and deposit the mucous 

 matter between the papillae ; but such an apparatus is not usually 

 admitted. 



It is probable, that the cuticle is placed at the surface of the body, 

 not simply to protect the corpus papillare ; but to prevent the constant 

 imbibition and transudation that might take place did no such envelope 

 exist. It exfoliates, in the form of scales, from the head ; and in large 

 pieces, from every part of the body, after certain cutaneous diseases. 



M. Flourens, 1 who has closely and accurately investigated the amv 

 tomy of the cutaneous envelope, considers that the skin of the coloured 

 races has an apparatus, which is wanting in the white variety of th^ 

 species. This apparatus he names pigmental, appareil pigmental. 

 It is composed of a layer (lame) or membrane which bears the pig- 

 ment, and of the pigment itself. Above it are two cuticles. In the 

 white variety the pigmental apparatus is wanting, and consequently the 

 skin is more simple than that of the coloured races. The skin of the 

 white variety approaches that of the coloured in some remarkable 

 points. First. The superficial layer or lame of the derma is every- 

 where of a peculiar appearance, which is different from that of the 



1 Anatomie Generale de la Peau et des Membranes Muqueuses, p. 34, Paris, 1843. 



