55 



in the pons varolii there is an immediate cessation of the 'cries 

 and of the agitation ; it merely remains an animal in whom the 

 circulation, the respiration and the other nutritive functions 

 are momentarily accomplished. 



On cats, rabbits and guinea-pigs, I have obtained a completely 

 different result in performing that experiment. After I had re- 

 moved, slice after slice, and from forwards backwards, the whole 

 encephalon, except only the medulla oblongata, I have found 

 that the mutilated animal, not only is much agitated, but cries 

 plaintively when it is pinched. If the medulla oblongata is also 

 removed, the cries cease, but the agitation still continues. 



According to these experiments, it is evident that the pons 

 varolii is not the only seat of sensibility, the centre of perception 

 of tactile impressions, as Longet calls it, and that either the 

 medulla oblongata is the seat of general sensibility or the cries 

 do not prove that there is a perception. 



Longet considers that the pons varolii is not only the centre of 

 perception for sensation of pain, but also for tactile impressions. 

 As to the tactile sensations he does not give the slightest appear- 

 ance of proof. Certainly neither the cries nor the agitation are 

 sufficient to authorize the opinion that the animal has felt a sen- 

 sation of tact. If the existence of cries could prove that there 

 is a perception of a tactile sensation, I should have to conclude 

 from my experiments that the medulla oblongata is the seat of 

 the faculty of perception of tactile sensations, for there are cries 

 after the removal of the whole encephalon except the medulla ob- 

 longata, and there are no more after the removal of this last 

 organ. If, instead of drawing conclusions from the existence of 

 cries, we take notice only of the agitation, we are bound to 

 conclude that the spinal cord is the seat of the faculty of percep- 

 tion of tactile sensations, for after this organ has been separated 

 from the medulla oblongata, agitation takes place when a limb is 

 pinched.* 



Cries and agitation may be attributed to a property of the 

 nervous centres, which is completely different from the faculty of 

 perception of painful or tactile sensations. That property is the 

 reflex faculty of the true spinal marrow ;f it is the property of 



* This conclusion is maintained as true by Senac, Caldarii, Kay, Legallois, 

 Paton, J. W. Arnold and many others, 

 f As Dr. Marshall Hall calls it. 



