30 OP LIFE. 



or of those muscles. But organic contractility always fol- 

 lows the excitement of organic sensibility; this is exem- 

 plified in the action of the heart from the stimulus of the 

 blood. 



Q. How do you explain this difference in the con- 

 nexion of the two sensibilities and contractilities? 



#. In animal life there is an intermediate power, the 

 brain, which may, or may not, at pleasure, follow animal 

 sensibility with corresponding contractility : we speak now 

 of the normal state of these parts. In organic life, there 

 is no such intermediate, controlling power; for the stimu- 

 lus to the organic sensibility, the blood for instance, im- 

 mediately acts on the contractility of the heart, and ex- 

 cites it to action. 



Q. Repeat the division of organic contractility. 



/?. Its forms are sensible organic and insensible organic 

 contractility. 



Q. Can you give examples of sensible organic contrac- 

 tility? 



*/?. You perceive it in the motion of the heart, in the 

 contractions of the stomach, especially in the act of vomit- 

 ing ; it is likewise sensible in the intestines. 



Q. What will exemplify insensible organic contrac- 

 tility? 



*&. The power by which the excretory vessels act on 

 their respective fluids, that by which the secretory organs 

 act on the blood which finds access into them, that which 

 the lymphatics exercise on the substances exposed to their 

 extremities ; these are all by virtue of insensible organic 

 contractility. 



Q. How does sensible organic contractility differ from 

 animal contractility? 



