EXTRACT XVIII. A. 



ON SECRETION, AND EXCRETION SO CALLED 

 SECRETION. 



SECRETION, as a word, or scientific term, signifies a separa- 

 tion from the blood of a fluid, meant for a physiological 

 use, or for excretion, as effete, or noxious, and hence is 

 applied to the functional work of a series of anatomical 

 structures called glands ducted, and unducted, or ductless. 



The view has hitherto been prevalently held, that the 

 material constituting the secretion was derived from the 

 blood directly, through the instrumentality of certain 

 secretory cells possessed by these glands, and this view 

 we are not about to dispute, further than that it should 

 be amplified, and should be made to include another 

 source of supply, viz. the nervine. Our reason, for 

 advancing this heterodox opinion is derived from a 

 survey of the circulatory and structural elements entering 

 into the histological composition of every gland, whose 

 circulatory contents are necessarily physiologically affected 

 by the specific secretory mechanism of those glands, from 

 their entry into, till their exit from, them. Circulation 

 within a gland, according to the results of our investi- 

 gation of the subject, is three-fold, in accordance with 

 the number of vasculatures histologically observable 

 therein, i.e. it consists of a blood circulation, a lymphatic 

 circulation, and a nervine circulation, the half of the first,, 

 and the last, of these, being afferent, and the remaining 

 half of the first, and the second, efferent. 



From this, we may conclude that the blood, and the 

 nervine circulations, are alone engaged in contributing 



