118 OF VITAL MOTION. 



(b.) Of the organic force^ not of a nervous cha- 

 racter, as an agent in the action of the heart. 



The immediate influence of the blood in this case 

 is not readily illustrated ; but it is not difficult to per- 

 ceive that the present theories upon this subject are 

 very unsatisfactory. That the blood does not stimu- 

 late contraction may be argued from the histories of the 

 common bloodvessels and visceral cavities, which have 

 been given in a former page, between which histories 

 and that of the heart there is an intimate connexion, 

 for whatever the diiFerences in form and function when 

 fully developed, they all spring from the same origin. 

 To suppose that the blood excites contraction in the 

 heart, moreover, is to create a difficulty which has 

 already been insisted upon ; for, if this were the case, 

 how is it that the blood finds entrance into the organ ? 



There need, however, be no doubt upon this ques- 

 tion if we institute once more a comparison between 

 the opposite conditions of plethora and anaemia. In 

 anaemia, for example, (especially in the variety which 

 is associated with the consumptive habit of body,) we 

 find rapidity and smallness of the pulse, together with 

 other signs of emptiness in the vascular system. There 

 is in fact the same evidence of contraction in the ven- 

 tricular cavities as was found in the state immediately 

 antecedent to syncope, for as we argued in this case, a 

 proportionate flood of blood must be sent into the 



