166 PHYSIOLOGY 



and many are not capable of managing those. Take away a sense from 

 some, they would be tolerably sensible. 



Of Sensibility arising from involuntary actions of Voluntary Parts. 



Although muscular action arising from the disposition of the muscle 

 itself, called spasm, is almost always attended with sensation more or 

 less, often [with] pain, and that very violent, yet this is not universally 

 the case; for I saw a gentleman who had involuntary contractions of the 

 orbicularis muscle of the left eye, and the muscles of the angle of the 

 mouth of the same side, and there was no pain, not even a sensation in 

 the muscle that acted. This is the first case of the kind I ever saw. 



What was also curious in this case was, that the antagonist muscles 

 seemed to have lost their voluntary power of action while the others 

 were acting involuntarily, as if they [the involuntarily acting ones] had 

 been acting at the command of the will ; and the antagonists accordingly 

 keeping at rest. 



Voluntary actions would appear to be as if the part were compelled 

 to act by the will. Those actions arising from the state of mind would 

 look as if they were only influenced by it. 



Sneezing is an involuntary act, arising from a local stimulus, and 

 requires a fuller inspiration than coughing. 



We can imitate coughing and do it with any degree of inspiration ; 

 but we cannot imitate a sneeze, even when we fill the chest full, for it 

 is a peculiar action. When I wanted to sneeze, when I had a rheu- 

 matic stitch in my back which deprived me of making a complete 

 inspiration, I could not ; but I could cough with the inspiration I was 

 able to make. 



The difference between coughing and sneezing is, that coughing is to 

 clear the throat, sneezing the nose. In the action of coughing, the 

 parts being moveable, adapt themselves to the operation, and it is an 

 operation of their own. But, in sneezing, the part that is to be cleared 

 is fixed, having no motion in itself ; therefore, to diffuse the air over 

 the whole surface as much as possible, the head makes a shake suitable, 

 and turning with the blast of air. 



Of the Senses. 



Of Seeing. 



The human is the only animal that judges of things in general by 

 the eye. It is the predominant sense in man ; therefore it becomes 

 more improved than the other senses, when some accident has cast the 

 scale in its favour for a greater frequency of action than them. We are 



