OF VITAL MOTION. 59 



neighbouring great vessels when completely evacuated 

 of their contents. It is also observed, that on irri- 

 tating a heart with the point of a knife, or any other 

 instrument, the first change was the production of 

 dilatation ; and further, as showing the activity of this 

 state, it is said that the force of the diastole as felt by 

 grasping the heart, and the force of the systolic con- 

 traction as felt by placing the fingers in the ventri- 

 cular cavities, are equally great so far as may be 

 judged by this coarse experiment. This fact had 

 been observed before Bichat's day, and it has been 

 since corroborated by Cruvelhier, and other observers 

 of considerable authority. 



In each system of muscular structures it would 

 appear therefore that there are two modes of motion, 

 one of contraction, and another of an opposite cha- 

 racter. And to show the definitiveness of the idea 

 which Bichat possessed in relation to the latter mode, 

 he concludes his remarks on this important subject by 

 hinting at some analogy between this quasi-state of 

 expansion, and that more conspicuous movement of 

 this character which is seen in the iris and in the 

 several forms of erectile tissue. 



The actual nature of this twofold change, 

 however, is only to be understood after a careful and 

 particular examination of the individual phenomena of 

 muscular action ; but before we proceed to this there 



