CHAPTER IV. 

 SECRETION. 



Secretion and Excretion. Ordinarily the product of 

 glandular activity is spoken of as a secretion. On the one 

 hand, glands may take from the blood substances which are 

 formed in that fluid, which would accumulate and pro- 

 duce detrimental effects if not removed, and which are dis- 

 charged from the body. On the other hand, glands may 

 form out of materials furnished by the blood substances 

 which are peculiar to that gland's activity, which have an 

 office to perform in the economy, which do not accumulate 

 on removal of the gland, and which are not discharged from 

 the body. The product in the first case is an excretion, in 

 the second case a secretion. But when it comes to naming 

 an exclusively excretory or exclusively secretory gland, 

 the task is found to be practically impossible. Probably the 

 most typical excretion of the body is the urine, yet there' are 

 in the urine substances, like hippuric acid, etc., which are 

 undoubtedly formed by the kidney, and which do not pre- 

 exist in the blood. The succus entericus, e. g., would seem 

 as typical a secretion as it is possible to find, but not infre- 

 quently it contains urea when the activity of the kidney is 

 impaired, to say nothing, under normal conditions, of the 

 water and salts which are taken as such from the blood. The 

 liver is notable in its secreto-excrementitious action. While 

 the desirability of thus separating the glands into secretory 

 and excretory and their products into secretions and excre- 

 tions is granted, the impossibility of such a division is appar- 

 ent. 



It is possible in most cases to apply the distinction to the 

 separate constituents of the product of a particular gland, 



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