PHENOMENA OF MUSCULAR MOTION. 291 



by food in the stomach, blood in the heart, urine in the blad- 

 der, &c. 



It has often been inquired whether the 

 whole bulk of a muscle is diminished or 

 increased by its contraction. It now seems 

 generally agreed that the bulk is not increas- 

 ed ; and, if there is any real diminution of 

 the fibre itself, it is very small indeed. 



The irritability of the muscular fibre, or 

 its power of contracting upon the application 

 of stimulus, exists in a greater degree in 

 some muscular parts than others. It is sus- 

 pended by the application of narcotic sub- 

 stances ; and it remains, in many cases, a short time after the 

 vital functions have ceased. 



In a majority of cases a general contraction seems to take 

 place in the last moments of life ; and after death the body is 

 stiff in consequence of it ; all the movable parts being fixed in 

 the precise situation in which they were when the vital motions 

 ceased. The limbs being generally in a bended position at that 

 time, if an attempt be made to extend them it will be very 

 evident that the contracted state of the muscles impedes this 

 extension. When this contraction is once overcome, the limbs 

 continue perfectly flexible, and the muscles are ever after 

 relaxed ; but the force of contraction is sometimes so great that 

 it will require a considerable exertion of strength to overcome 

 it. This condition of the muscles, after death, although very 

 common, is not universal : and some dead subjects are perfectly 

 relaxed and flexible from the first cessation of the vital func- 

 tions. 



The force with which muscles contract exceeds greatly their 

 inanimate power of cohesion. Thus, a muscle deprived of life, 

 would be completely lacerated by a weight suspended from it, 

 which it could readily raise by its contraction during life. This 

 force of contraction is so great, that the tendo-achillis and the 



* The same muscle at the moment of contraction, and a b c f indicates the 

 same, as in Fig. 71. 



