146 



which immediately within the mouth is pretty equal in breadth 

 throughout. They do not resemble in shape, therefore, nor as we 

 shall afterwards see in structure, the flask-shaped glands of the skin 

 of Amphibia. 



The margins of the openings of these glands are thick, rounded, al- 

 most papilliform; and their cavities, in the recent state, filled with 

 small epithelial cells in various stages of development. When 

 the latter are removed, the interior of the gland is seen to be lined by 

 a layer of small, flattened, nucleated corpuscles, which, by pressure, 

 may be forced out into the field and broken into irregular patches. 

 These corpuscles are not completely flattened ; are more or less regu- 

 larly hexagonal, granular, and furnished with a nucleus which is im- 

 bedded in a number of elementary granules. It is seen also that 

 these corpuscles rest on, and are attached to, a very delicate, almost 

 homogeneous membrane, which, on the addition of ammonia, be- 

 comes distinctly granular. Lining the cavity of the follicle this mem- 

 brane may be traced towards the free surface of the skin, in which it 

 becomes lost to view between the epithelial and pigmentary layers. 

 This membrane is the analogue of the primary membrane of the mu- 

 cous and serous tissues ; it is the basement or germinal membrane of 

 that modification of the former termed skin, and though it cannot be 

 distinctly demonstrated in the interfollicular portions of the integu- 

 ment, no reasonable doubt can, in this case, be entertained of its con- 

 tinuity throughout. In the present case, the pigment of the skin 

 appears to occupy a somewhat anomalous position. In the higher 

 animals it is said to occur in the inferior or young layer of epithelium 

 cells, and is situated externally, therefore, to the supposed seat of the 

 germinal membrane. In the tribe of animals under consideration, it 

 would seem to be the reverse; for although numerous pigmentary 

 granules are found in the epithelial cells, by far the greatest part of 

 the cutaneous pigment is placed beneath the germinal membrane, is 

 granular, occurs in rounded or stellar masses, and is not situated in 

 the interior of cells, though it may possibly have had a cellular origin. 

 The deep surface of this germinal membrane of the follicles is 

 surrounded by a thick layer of inelastic fibrous tissue, which gives 

 support to and determines the form of the gland. This layer is com- 

 posed of distinct fibres, which appear as if regularly woven into each 

 other, and which at the mouth of the gland are lost in the fibrous ex- 

 tension lying beneath the germinal membrane, and containing in its 

 meshes the granular pigment of the skin. 



