224 



MUSCULAR- SYSTEM. 



animal contractility; opium thrown into contact with the 

 muscular texture; all these alter the contractility of the 

 muscles. 



Q. Repeat the actions necessary to excite animal con- 

 tractility in the muscular tissue? 



*#. The action of the brain which originates, that of 

 the nerves which propagates, and that of the muscles 

 which receive the principle of motion. 



Q. What causes acting on the brain produce animal 

 contractility? 



*#. The exercise of the will ; and there are involuntary 

 ones which excite this property without the concurrence 

 of, or even in opposition to the will. These involuntary 

 causes are directly applied to the brain, or influence that 

 organ by sympathy. 



Q. Are these sympathetic impressions always attended 

 with increased determination of blood ? 



*#. They are not; it is irritation simply; and this irrita- 

 tion excites the brain to a degree beyond the control of 

 volition, and convulsions ensue. 



Q. How does fear act on the muscles? 



#. Through the intervention of the brain, and this fear 

 deprives the brain of its power to originate the impulse of 

 the contractility. 



Q. How do you account for muscular action in the 

 foetus, where the will evidently cannot act? 



*/2. Sympathetic impression, derived from the visceral 

 organs, acts on the brain producing involuntary muscular 

 action or animal contractility. 



Q. Can you explain the muscular motion after decapita- 

 tion in man and animals? 



#. The brain conveys for a short time lo the face, and 



