PHYSIOLOGY OF THE CIRCULATION. 63 



ON CERTAIN POINTS IN THE 



MECHANISM AND PHYSIOLOGY OF THE 

 CIRCULATION OF THE BLOOD. 



[From the LONDON MEDICAL GAZETTE, 1844.] 



SINCE the discovery of the circulation by Harvey, 

 numerous and important functions have at different 

 periods been assigned to it; and every year tends 

 to add to their number. Thus, among other uses, it 

 is generally recognised as the instrument by which 

 nutriment is conveyed to every part of the system, 

 and eifete and noxious matters are transmitted to 

 their proper points of discharge. But while all 

 agree in regarding the circulation as a chief means 

 of intercommunication and transport, there is an 

 extensive and highly important class of functions, in 

 the production of which this agent is, by the majority 

 of physiologists, considered to exert but a partial and 

 secondary influence. The functions to which I 

 allude, all involve either the discharge through the 

 coats of the minute blood-vessels of certain matters 

 previously present in the blood ; or the entrance of 

 various external substances into the mass of circu- 

 lating fluid. Under the former of these divisions 

 may be mentioned 



1st. Nutrition, or that process by which a con- 

 stant supply of their proper aliment is furnished 



