268 SECRETION. 



the chemical relations of the various particles, existing quite in- 

 dependently of life, and perhaps aided by the length and dia- 

 meter of the vessels and other mechanical circumstances, are 

 brought into play circumstanced so as to become efficient 

 by the vital powers. How, we know not. But life cannot create 

 any more than it can annul the physical or chemical qualities 

 of matter ; nor can it create matter. It may counteract one 

 inanimate force by opposing to it another inanimate force ; it 

 may render one inanimate force efficient by withdrawing op- 

 ponent inanimate forces. But this is all ; how it accomplishes 

 this, is yet unknown. 



Secretion does not depend on the mind, though, like every 

 function, much influenced by it. Fear increases the production 

 of urine, rage dries up the mouth ; any depressing passion will 

 vitiate the milk. How far it depends upon nervous influence we 

 shall consider when speaking of the nervous system. 



" There is this difference among the various fluids secreted by 

 the organs arid powers now described, that some pass to the 

 place of their destination immediately, while others are depo- 

 sited in receptacles, and detained there for a length of time, be- 

 coming more perfect before their excretion. The milk in its 

 ducts, the urine, bile, and semen in their respective bladders, and 

 in some degree the serum of the vesicles of De Graaf, are ex- 

 amples of this." 



The more watery portion is absorbed, and therefore, the longer 

 the stay in the ducts or receptacles, the more consistent does the 

 fluid become. If the stay is considerable, the other portions 

 also are absorbed, as seen in the case of jaundice from obstruc- 

 tion of the ductus hepaticus or choledochus. The detention of 

 the urine is not for the purpose of perfecting it, but for con- 

 venience. 



