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STUDIES IN ADVANCED PHYSIOLOGY. 



a gland is but a surface of secreting cells supported by a base- 

 ment membrane, richly supplied with blood-vessels under- 

 neath the membrane, and subject to the control of nerves. 



Fig. 97. FORMS OF GLANDS. SIMPLE SACCULAR GLAND FROM AMPHIBIAN SKIN. (Flem- 

 ming.) SIMPLE TUBULAR GLAND FROM HUMAN INTESTINE. (Flemming.) GLAND 



FORMED OF A SIMPLE DUCT-SYSTEM. (Flemming.) CONSTRUCTION OF A LOBULE OF 



A COMPOUND RACEMOSE GLAND (a, duct; &, 6, branches of duct; c, secreting alveoli). 

 PART OF A SMALL RACEMOSE GLAND, SHOWING THE TUBULAR CHARACTER OF THE 

 ALVEOLI. (Flemming.) 



A gland, however, spread out as such a flat surface, 

 would take up a very great deal of room in order to secrete 

 the amounts necessary to the body. To save space, there- 

 fore, these glandular surfaces become pitted in and folded, 

 and in this manner result the various forms of glands. Ex- 

 amples of the typical surface glands are not wanting. Thus, 

 the peritoneum, the pleura and the pericardium have such 



