vni CUTANEOUS GLANDS 129 



In this, as well as in the other sections described in the 

 present chapter, the structure of the nuclei of the various 

 cells can be more easily made out than in the fresh prepara- 

 tions you have already examined. Each nucleus will be 

 seen to be enclosed by a definite nuclear membrane, and to 

 contain in its interior a number of minute bodies, which 

 take up the stain more deeply than the rest of the nucleus. 

 One or more of these bodies may correspond to the nucleoli 

 already seen (p. 109), but many of them are of a different 

 nature and can often be seen to form a network : the material 

 of which these are composed is known as chromatin, and is 

 surrounded by a semi-fluid substance forming the ground- 

 work of the nucleus. 



Cutaneous Glands Secretion. In the superficial part of 

 the derm are seen numerous rounded spaces (Fig. 38, 

 c. gl, c.gl'\ each of which can be proved, by taking sections in 

 various directions, to be a nearly globular cavity, from which 

 a narrow canal (d), like the neck of a flask, passes through 

 the epiderm to open on the external surface. Both the 

 body and the neck of the flask are lined with epithelium, 

 the cells lining the body being nearly cubical, those of the 

 neck squamous. 



These structures are called cutaneous glands : they per- 

 form the function of manufacturing the slimy fluid which, 

 as we have seen, is constantly exuding on the surface of 

 the skin. The epithelial cells of the gland have the power 

 of forming minute droplets of the fluid out of the materials 

 supplied to them by the blood : the droplets escape from 

 the cells and accumulate in the interior of the gland, whence 

 the fluid is finally discharged by the duct. 



The cells lining the duct are continuous on the one hand 

 with those of the gland, and on the other with those of the 

 epiderm. The whole gland with its duct is to be looked 



PRACT. ZOOL. K 



