OF THE SECRETIONS IN GENERAL. 291 



NOTES. 



(A) " There are two classes of secreted fluids, viz. the secre- 

 tions, properly so called, or the fluids intended to fulfil some 

 ulterior purpose in the animal economy, and the excretions, which 

 are directly discharged from the body. The fluids of the former 

 class are all alkaline, and of the latter all acid. The excretions 

 are the urine, the perspired fluid, and the milk. All the other 

 fluids appear to belong to the former class. 



" The alkaline secreted fluids may be divided into two very 

 distinct species. The former of these contains the same quantity 

 of water as the blood, so that the change induced by the nervous 

 influence, seems to be confined to that of altering the chemical 

 form of the albuminous materials, * without affecting their 

 relative proportion to the water and other substances dissolved in 

 the blood. The bile, spermatic fluid, &c. are of this kind. The 

 latter species consists of fluids, in which the influence of the 

 nervous system has separated a large portion of the albuminous 

 matter, and left the remaining liquid proportionally watery. 

 The saliva, the humours of the eye, and the effused serum of 

 membranes, are of this species, and in these the quantity of 

 salts, and in general also of alkali, is the same as in the blood. 



" The influence of the chemical agent of secretion is, there- 

 fore, chiefly spent upon the albuminous materials of the blood, 

 which seems to be the source of every substance that peculiarly 

 characterises each secretion, each of which is mi generis, and is 

 its principal constituent. All the other parts of the secretion 

 seem to be rather accidental, and to be found there only because 

 they were contained in the blood out of which the secretion was 

 formed. Therefore, in examining the secreted fluids, the chief 

 attention should be paid to the peculiar matter of the fluid, which 



* This appellation Berzelius gives to the fibrine, albumen, and colouring 

 matter of the blood. 



u 2 



