

 PHYSIOLOGY OF THE CIRCULATION. 91 



PART II. 



OP THE MECHANISM OF ABSORPTION ; IN WHICH IT IS ATTEMPTED 

 TO TRACE THAT ACTION TO THE PECULIAR PHYSICAL CON- 

 DITIONS REGULATING THE PASSAGE OF THE BLOOD INTO AND 

 THROUGH THE VEINS. 



BEFORE mentioning the facts which appear to me 

 calculated to illustrate the mechanism of the opposite 

 function of absorption, it may be well briefly to re- 

 view one or two of those opinions on the subject 

 which have already been presented to the public. 



I have previously had occasion to notice Magen- 

 die's general doctrine as to the transmitting power 

 possessed by membranes; and have given some 

 reasons for my disbelief in the sufficiency of that 

 explanation of the various processes of exudation 

 and absorption. The latter function, however, is by 

 the same authority still more explicitly declared to 

 depend upon an affinity of the vascular walls for the 

 substances absorbed.* But while acknowledging the 

 great value of many of the laws regulating animal 

 absorption which have been established by the la- 

 bours of this eminent physiologist, I cannot perceive 

 that the experiments adduced in support of this par- 

 ticular doctrine do more than prove the porosity of 

 membrane ; for they appear mainly intended to show 

 that the same interchange of fluids which takes place 

 through inorganic porous' septa, will, under similar 

 circumstances, also occur through animal membrane. 



* " Journal de Physiologic," t. i. p. 6. 



