132 ON THE NATURE AND PRINCIPLES OF 



till such time as the accumulation of a mass of fresh 

 facts shall enable us to deduce laws capable of dis- 

 pelling the darkness and mystery in which they are 

 now enveloped. 



P/VRT II. 



OF THE HKALTIIT FUNCTIONS OF THE MINUTE BLOOD-V1.-M.I>. 



As it is utterly impossible to form any correct idea 

 of the nature of a morbid action without having first 

 thoroughly understood the uses served in their 

 healthy state by the particular structures affected, 

 it is unnecessary to apologise for the introduction, 

 in this place, for a few remarks on the physiology of 

 the circulation ; and as the minute blood-vessels are 

 universally admitted to be the seat of the important 

 disorders now under consideration, we cannot satis- 

 factorily engage in the pathological inquiry without 

 first endeavouring to determine the nature of their 

 healthy functions, and, as far as possible, the means 

 by which those actions are accomplished. It is, 

 perhaps, in the present advanced state of physiology, 

 scarcely necessary to combat the proposition so long 

 and so tenaciously maintained, that the arteries and 

 capillaries contribute some active share towards the 

 motion of the blood the power of the heart being 

 supposed to be inadequate to this task. I may, 

 however, remark that it is as impossible to demon- 



