ORGANIC FUNCTIONS. \) 



that is made of it in the renovation of worn-out parts, and 

 in a state of decay. The process is likewise called nutrntioii. 

 As the organs lose their vigour from constant use, thev are 

 removed by absorbent vessels, and fresh matter is deposited 

 by the arteries, or nutrient vessels. In this manner a continual 

 change of material is kept up, which is so complete that the 

 body an animal possessed at one period, is really not the body 

 he has inhabited at some time subsequent. The growth of the 

 body, and its decline, both admit of explanation, on the 

 presumption, that, during growth, the arteries deposit as 

 equal to two, the absorbents acting as equal to one; that 

 in middle life these operations are equivalent ; but that in 

 old age the nutrient powers fail, while the absorbent con- 

 tinue to act with no abatement of vigour. 



The animal fluids are the blood ; the fluids that enter the 

 blood ; and the fluids that proceed from the blood. 



The fluids which enter the blood are of two kinds : 

 1. Those by which it is renewed and enriched; 2. Those 

 which enter it, in order that they may be conveyed out of 

 the body. 



Although we cannot doubt that any considerable modi- 

 fication of the chyle, by aliment or by air, must influence 

 the composition and quality of the blood, we have no 

 means of ascertaining w^hat these modifications are. Nor 

 can we doubt that the absorbed matters from the body alter 

 and contaminate the blood, and act as poisons upon the 

 system, as they may be absorbed from parts diseased or putre- 

 fying. In this way, doubtless, disorders at first purely local 

 become constitutional. 



The BLOOD may be regarded as the medium through 

 which these changes are eff'ected. It receives fresh supplies 

 from the cavities of the bowels ; it animalizes this matter ; 

 it likewise receives the old and worn-out particles absorbed 

 from diff'erent textures of the body, and conducts them into 

 the channels designed for their separation and expulsion. 



Again, matters which are harmless in minute quantities, 

 become noxious when retained or accumulated in the blood, 

 from faulty or deficient action in the organs destined to 



