CHAPTER I 



HOW THE GLANDS OF INTERNAL SECRETION WERE 

 DISCOVERED 



Just what are the glands of internal secretion? And how have 

 we become possessed of whatever information about them we 

 have? A brief review of how the idea of a gland of internal secre- 

 tion came into the human mind and of the contributions that 

 have converged into a single body of knowledge i3 worth while. 



A gland is a collection of cells (those viscous globules which 

 are the units of all tissues and organs). It manufactures sub- 

 stances intended for a particular effect upon the body economy. 

 The effect may be either local or upon the body as a whole. 



Originally, a gland meant something in the body which was 

 seen to make something else, generally a juice or a liquid mix- 

 ture of some sort. A classical example is the salivary glands 

 elaborating saliva. The microscope has shown us that every 

 gland is a chemical factory in which the cells are the workers. 

 The product of the gland work is its secretion. Thus the sweat 

 glands of the skin secrete the perspiration as their secretion, the 

 lachrymal glands of the eyes the tears as theirs. The collec- 

 tivism of management and control is the only essential difference 

 between them and the modern soap factory or T.N.T. plant. 



Man as a carnivor, and as a consequent anatomist, has been 

 acquainted with these more superficially placed glands for some 

 thousands of years. During all this time and during the epoch 

 of the achievements of gross anatomy, it was believed that the 

 'ions of all glands were poured out upon some surface of 

 the body. Either an exterior surface like the skin, or some in- 

 terior surface, the various mucous membranes. This was sup- 

 1 by the discovery of canal-like passage ways leading from 

 !:u)(l to the particular surface where its secretion was to'- 

 act. These corridors, the secretory or excretory ducts, are pres- 

 ent, for example, in the liver, conducting the bile to the small 

 intestine. Devices of transportation fit happily into a com- 

 parison of a gland to a chemical factory, corresponding thus 

 closely to the tramways and railroads of our industrial centers. 



