vra CUTANEOUS GLAXDS 129 



the present chapter, the structure of the nuclei of the 

 various cells can be more easily made out than in the 

 fresh preparations 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 sur- 

 rounded 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 dis- 

 charged 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 



PR ACT. ZOOL. T 



