620 CIRCULATION OF THE CAPILLARIES 



elevated from seventy-two to one hundred and 

 thirty beats per minute : and so permanent was 

 its influence on the circulation, that the action 

 of the heart was not reduced to its natural fre- 

 quency for five hours. It is therefore manifest, 

 that in all cases of languid circulation, from what- 

 ever cause produced, we should apply that re- 

 medy on which its healthy vigour depends. By 

 means of the warm bath, we can arouse the cir- 

 culation of the whole system ; and when the 

 stagnant blood is dark coloured, we can change 

 it to a bright florid hue, accelerate its passage 

 through the lungs, and thus augment the func- 

 tion of respiration ; as will further appear when 

 I come to treat of its therapeutical agency. 



It now remains to inquire what impels the 

 blood through the arterial capillaries, and causes 

 its return through the veins to the right side of 

 the heart. Magendie and many other Physiolo- 

 gists maintain, that both are owing to the heart's 

 action alone, because they are diminished when- 

 ever the arteries which supply them with blood 

 are secured by ligatures. But when the arteries 

 are tied, not only is the supply cut off, but the 

 blood no longer receives the vitalizing influence 

 of respiration. That the office of the heart is 

 to convey blood from the lungs to the arterial 

 capillaries, cannot be doubted ; but that it is 

 not any further essential to the capillary circu- 

 lation, would appear from the following facts : 



