372 THE SK1X AND THE SEXSE-OIIGANS. 



The epidermis covering the papilla is well supplied with nerve-fibres, derived from 

 large ganglion-cells in the papilla (Fig. 232 III). The branched pigment-cells, so 

 numerous in the rest of the skin, are absent from the upper parts of the papillae 

 (Fig. 232 II) ; the pigment-cells may cease either abruptly or gradually. 



The rose-colour of the papillae is due to the presence of a golden red pigment. 

 After the breeding season the papillae are gradually lost, and the pigment-cells 

 wander into the unoccupied parts. 



Huber compares the arrangement of the nerves to that of the ' touch-spots ' of 

 Merkel. 



d. The glands of the skin are of two kinds, serous and mucous ; 

 they have been fully described by Engelmann and Openchowski. 



(i) The serous glands (Kornerdriisen, Engelmann) are large, 

 averaging- in diameter 0*2 o '4 mm., but others vary in size from 

 0*13-0' 8 mm. in diameter. They are found chiefly on the dorsum 

 of the trunk and arranged in groups, which vary in dimensions 

 from 320 mm. in length and 24 mm. in breadth. They may be 

 found in any part between the ear-region and the anus, on the 

 dorsal surface of the thigh, especially towards the outer and inner 

 borders. They are found very sparsely distributed on the ventral 

 surface of the trunk and on other parts of the extremities, though 

 as a rule a few are found on the dorsal surface of the feet and near 

 the phalanges. They are wanting in the nictitating membrane. 



The glands have a rounded form, with the ducts placed at their 

 superficial poles. The glands possess three coats ; externally is a 

 coat of connective-tissue, the fibres of which are arranged closely 

 together, and cross one another at acute angles : these fibres are con- 

 tinuous with the connective-tissue of the surrounding cutis. Inside 

 this coat is a thick layer of muscle-fibre (o'OO5-O'Oi5 mm.); the 

 muscle-cells are arranged meridionally, with the one pole towards 

 the superficial surface of the gland, the other pole at the deep surface 

 (Hensche). Many of the fibres, however, extend only one-fourth or 

 one-third of this distance. 



The innermost coat is a simple layer of epithelial cells, which 

 rests directly on the muscle-layer ; no basement-membrane or space 

 of any kind having been discovered between the two layers. When 

 examined in the recent state these cells are conical or cylindrical in 

 shape, and have the appearance of goblet-cells : they possess a 

 delicate but distinct cell-wall, but are open towards the lumen of the 

 gland. One or sometimes two rounded nuclei are found towards 

 the base of the gland, and surrounded by a small amount of gran- 

 ular protoplasm ; the rest of the cell is occupied by a mass of small. 

 rounded, highly refractive granules of about O'002-O'Oi mm. in 



