28 PROPERTIES OF MATTER 



the one, a Remora is caused by the friction of 

 the water upon the containing vessel ; in the 

 other, the power of the containing vessel is the 

 cause of the velocity in the fluids they convey. 

 In the former, the distribution is regular and 

 uniform ; in the latter, we constantly behold it 

 altogether different ; being often increased, or 

 diminished, throughout the same parts, at dif- 

 ferent times. A mere blush in the face deci- 

 dedly proves, that, although vessels the most 

 extreme and minute, possess a power common 

 and concurrent with the vascular system at 

 large, they are, nevertheless, endowed with 

 an exclusive one also. In the former, the 

 water remains unaltered and unchanged ; in 

 the latter, the blood suffers a constant alteration 

 in its nature. 



If the effects of the fluids upon the vessels of 

 both be examined, we shall find them to be, in 

 each, totally different; the effect which is 

 caused by the pressure of fluids upon solids, 

 and of solids and fluids upon each other, how- 

 ever small that pressure may be, is invariably 

 attended with mechanical destruction, and loss 

 of substance.* In the one, the degree of me- 

 chanical destruction altogether depends on the 

 quantity of pressure applied, and of motion pro- 



* In the living system, instead of a waste being produced, 

 an increase of substance generally ensues. 



