CHAPTER XVIII 

 THE DUCTLESS GLANDS 



364. The ductless glands are organs whose functions 

 are not yet well understood. Unlike other glands, they 

 do not form a definite secretion poured forth by means of 

 ducts. Some of what we call " true glands " have been 

 shown to send into. the lymph and blood, in addition to 

 the secretion passing through their ducts, material of great 

 importance to the healthy working of the body. This is 

 true of the liver and of the pancreas, though these addi- 

 tional functions are only partly understood. It is probable 

 that the ductless glands have similar offices in the economy 

 of the system. 



365. The Spleen (Figs. 94 and 95, pp. 163 and 165). 

 The largest of these peculiar glands is the spleen, a dark 

 purplish body of variable size and spongy texture, lying on 

 the left side of the abdominal cavity, just below the stom- 

 ach. In the meshes of the tissue of the spleen is a soft sub- 

 stance called spleen pulp. This consists largely of red 

 blood corpuscles and colorless cells, some of which are like 

 the white blood corpuscles. 



366. The Blood Supply of the Spleen. The splenic artery, 

 a branch from the aorta, carries an abundant supply of 

 blood to the gland (Fig. 94), and the smallest branches 

 of the artery open directly into the spleen pulp. This 

 is the only place in the body where the blood comes 



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