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ELEMENTARY PHYSIOLOGY 



pinching or cutting ; or by electrical irritation, such as is produced by the 

 electric shock ; or by chemical stimuli, such as irritant poisons. 



Muscles may be made to respond to stimuli not only during life, but also 

 shortly after death has occurred. Thus, the limbs of a recently killed frog 

 may be made to jump violently by sending an electric current through them. 



Just after death, the muscles of an animal are soft and pliant 

 as during life ; but after a short time they become so stiff and 



Fig. 5 1. Back View of the Muscles 

 of the Trunk. 



Fig. 52. Back View of the 

 Muscles of the Arm. 



The large central muscle of the upper 

 arm is the biceps muscle. 



hard that it is impossible to bend the limbs without a danger of 

 injuring the bones or joints. This death-stiffening, or rigor 

 mortis, is due to the coagulation (Lat. co, together, and ago, I drive) 

 of a fluid substance in the muscle, called myosin. In the human 



