PHYSIOLOGY. 85 



preternatural mode of contraction, except that which we call 

 spasm, and which I have endeavoured to explain. 



" The state of spasm, strictly so called, consists in two dif- 

 ferent circumstances; the one is the degree of contraction, 

 which is greater than what happens in the ordinary exercise of 

 our functions ; the other is, that in this state the contraction 

 does not follow the more general law of alternation with a relax- 

 ation, nor readily yields to extending powers applied ; we may 

 suppose these two circumstances are strictly connected together, 

 and that the rigidity or inflexibility depends upon the degree 

 of contraction. Possibly it does so ; but what I want to observe 

 is, that there is a state of contraction short of spasm, which is 

 attended with a resistance, or with some difficulty in admitting 

 of distention, so that much less distention will give considera- 

 ble pain. That such a state as this takes place upon occasions, I 

 think we cannot doubt. I find it a common consequence of spasm. 

 I have frequently an opportunity of observing this in myself: I 

 am liable to be affected with spasm ; and when it is remitted, there 

 is still a manifest rigidity in the muscles which were affected by it, 

 so that they do not yield, as before, to distention by the power 

 of their antagonists, or by extending powers being applied. 

 The same takes place in strains. It is well known that any 

 more violent exertion is very ready to throw the muscles into a 

 spasmodic state, so that the parts are overstretched, in conse- 

 quence of which they not only recover their natural state of 

 contraction, but go further to the spasmodic, so as to retain a 

 certain degree of rigidity for a long time after. It has been a 

 mistake to view the case of strain as a case of flaccidity, and 

 too great a degree of flexibility in the part ; there is rather a 

 state of rigidity and contraction in the part. We have several 

 instances of this, in consequence of what may be called strains. 

 Thus, when a man is stooping, and exerting a considerable 

 force in lifting a weight, and has a sudden spasm coming to 

 certain muscles in his back, it affects him with such a rigidity 

 that he is not able to bend his body again. I say the same state 

 constantly occurs in what we call chronic rheumatism ; and as 

 this is most commonly the sequel of the acute, it points out, 

 that when the overstretching of the blood-vessels, which takes 

 place in acute rheumatism, ceases, they fall into this state 



