NERVOUS SYSTEM. 91 



JL. Because there is so little animal sensibility in the 

 nervous coat. 



Q. What effect has repeated irritation on the animal 

 sensibility of nerves? 



/?. It is gradually diminished, and by rest is reac- 

 cumulated. 



Q. What are the peculiarities of nervous animal sensi- 

 bility? 



J2. Observe the peculiarity of pain in the different or- 

 gans; how the sensation of pain in the dermoid texture, 

 for instance, differs from that in the muscular or osseous 

 texture. Another feature interesting to the physician and 

 surgeon is, that the trunk of a nerve partially irritated, 

 the animal sensibility will often be exalted in all the 

 branches; as when pain is felt along the forearm when 

 the cubital nerve is compressed or struck at the elbow; 

 this is further illustrated in tic doloureux, and in irritation 

 of points of the sciatic nerve. In these the irritated point 

 is a centre from which painful irradiations are diffused. 



Q. Does the increase of animal sensibility ever take 

 place between the injured point and the brain? 



*fl. It does not; it is an affection continued along the 

 branches. 



Q. What example is given to illustrate the different 

 animal sensibility or pain in different textures ? 



t/#. The case of a man is related by Bichat, who in the 

 course of an amputation, asked the surgeon why it was 

 that the pain in cutting through the skin was so different 

 from that felt in the division of the muscles. 



Q. How many kinds of sensation arise from the inter- 

 nal sensitive principle? 



#. Two the external and internal. 



