CHAP. XXX. 



SECRETION, EXCRETION, ABSORPTION, AND 

 NOURISHMENT. 



General Jffitfs of Secretion. The Gland f. Excretion. Secretion ef 

 Bile.'*~Ho<w this Function is performed in Fifies.-^Abjorption. 

 Lymphatic Glands. Nourijbment or Reparatim of the Body, Bones 

 become morefolid in old Age. 



THERE is no function of the body which is 

 more calculated to excite our aftoniihment and 

 admiration, than that of fccretion. By fecretion we 

 fee one fluid, the blood, modified more varioufly and 

 more exquifitely than the human mind can eafily con- 

 ceive, or ever hope to explain j in one part, fecreted 

 fluids, varying in different races of animals according 

 to their food, are endued with a power of dlfiblving 

 the aliment, and fitting it for the nonrifhment of the 

 body ; in other parts, fecretion furnifhes fluids for lu- v 

 bricating the organs concerned in the various functions 

 of the animal machine. In fome animals the moil 

 powerful odours, in many the moft deadly poifcns, and 

 in all, that wonderful fluid by which their race is per- 

 petuated, are the products of fecretion. 



So far are we from difcovering the nature of fecre- 

 tion, and the caufes of the different properties of the 

 fluids which are fecreted, that we in reality know little 

 more of this function, than the general outlines of the 

 ftructure of the parts concerned in it. iVe fee a gland, 

 with an artery, vein, and excretory du6l connected to 

 it, but whether the fecreted fluid is formed by exuda- 

 tion through the coats of the minute arteries dif- 

 x tributed 



