OF VITAL MOTION. 77 



We are able also to form some conjecture as to the 

 reason why complete contraction should not be the 

 inevitable consequence of the cutting off of nervous 

 influence. We learn, indeed, on the authority of 

 Longet and other experimental physiologists, that the 

 irritability of a muscle continues for a much shorter 

 time after the ligature of the artery, than after the 

 division of the nerve; and we may infer, therefore, 

 that so long as the circulation continues there may be 

 a sufficient amount of vital activity to prevent con- 

 traction, notwithstanding a complete interruption in 

 the supply of nervous influence. And this conclusion 

 is the more probable when it is considered that the 

 phenomenon of rigor mortis does actually occur in 

 paralysed muscles when the circulation is suspended 

 by death. 



It need be no fatal objection, therefore, that para- 

 lysis of motion, instead of contraction, should at times 

 mark the suspension of innervation ; for a slight varia- 

 tion in the condition of the circulation may be suffi- 

 cient to produce this difference in the result. Indeed, 

 paralysis may after all be the first phase of con- 

 vulsion. 



