IN THE KIDNEY. 35 



the co-existence and co-operation of two essential 

 causes, each of which will, in different individuals, 

 vary much in its amount of activity or degree of 

 completeness. 



The momentum of the arterial blood arising from 

 the contractions of the ventricle constitutes the 

 active force from the operation of which the com- 

 pression takes place. But as a counter resistance 

 is required before an intense degree of the latter 

 state can occur, it is only when some extraordinary 

 obstruction to the free passage of the blood through 

 the smaller vessels exists that the effects of an undue 

 compression of that fluid are perceptible. 



It follows, therefore, that the momentum being 

 equal in a number of cases, the intensity of the 

 compression of the blood will be proportioned to 

 the completeness of the obstruction: and, on the 

 other hand, the impediment or obstruction being 

 equally complete, the degree of compression will 

 then be commensurate with the amount of the 

 momentum. 



The whole of the preceding experiments, if care- 

 fully considered, will, I think, support this state- 

 ment. 



They also prove 



1. That simple compression of the blood in its 

 smaller vessels will, in a direct ratio to the degree 

 of intensity of that compression, cause the exudation 

 of an albuminous fluid, of coagulating lymph, or the 

 extravasation of blood. Its immediate effects, there- 

 fore, precisely resemble those of inflammation : and 



as it is well ascertained that both the essential causes 



v 2 



