THE SKIN AND ITS APPEXDAG. 369 



[The horny layer is, for the most part, very thin, as it consists of 

 one or two layers of flattened cells only (Schultze), but in some 

 situations, as on the back and especially on the under surface of the 

 toes, it is much thickened, and is then rough. 



Deeply pigmented, branched cells, capable of contractile move- 

 ments, are also found, somewhat sparsely distributed, in the epi- 

 dermis (Leydig, H. Muller, Schultze).] 



b. The cutis (Fig. 229, Co, Co 1 , Co z ). The epidermis is generally 

 attached to the corium by means of a continuous layer of branched 

 cells, which is deeply stained when the animals are fed with 

 madder (Katschenko). Many of these cells are pigmented. This 

 layer is seldom flat, but is raised into papillae and folds, which are 

 repeated by the superimposed epidermis. In addition to this layer 

 the corium has, except in the webs and supplemental toes, three 

 distinct layers of connective-tissue, together with much unstriped 

 muscle-fibre (Eberth). 



The superficial layer (Fig. 229 Co) is a loosely-meshed, much 

 pigmented, vascular layer ; it forms a loose support for the nu- 

 merous glands, and is traversed by numerous nerves. 



The middle layer (Co 1 ) forms the groundwork of the cutis; it 

 is much firmer and more compact than the superficial layer ; in 

 section it appears as a broad band, bounded superficially by a sharp 

 line. It is chiefly composed of closely packed connective-tissue 

 fibres, which have, for the main part, a horizontal or wavy course ; 

 at certain points, however, vertical fibres are seen passing 1 towards 

 the surface and hiding the sharp contour (between Co and Co 1 ). At 

 such points the two sets of fibres form a sort of basket-work 

 arrangement. 



The deepest layer (Fig-. 229 Co 2 ) is composed of very delicate, 

 white and yellow elastic fibres, and vessels and nerves ; it attaches 

 the whole integument to the underlying organs. By the looseness 

 of its structure it forms an important lymph-space. 



[The muscle-fibre of the cutis is very unevenly distributed. It is 

 found somewhat freely in the region of the back, the dorsal surface 

 of the head, and the neck ; less freely on the dorsal surfaces of the 

 extremities, very sparsely on the abdomen, breast, and ventral sur- 

 faces of the extremities; in the feet it appears to be absent 

 (Eberth). 



The pigment of the skin. As already mentioned pigmented cells 



Bb 



