CHAP, in.] OF MOTRICITY. 391 



any point of the skin determines convulsive movements almost 

 general, while in the perfect animal, we can sometimes touch the 

 central end of a cut nerve without exciting the smallest reflex 

 movement. 



In many vertebrates decapitation by no means hinders reflex 

 movements, complex and associated, having all the appearance of 

 voluntary movements. All the world has heard the celebrated 

 experiments of Flourens spoken of, so often repeated and varied 

 since. Deprived of its cerebral hemispheres, a pigeon still flies 

 when we throw it into the air, swallows grain when we put it 

 into its mouth ; and so on. The experiment is always the more 

 striking, the more the vertebrate is inferior, and the less brain 

 it consequently possesses. For instance, a fish without brain 

 swims as well as a normal fish. If we pinch the skin near the 

 anal orifice of a decapitated frog, we see the posterior feet of 

 the animal directed towards the irritated point, then extended 

 suddenly, as if to repel the aggressor. If we pinch laterally the 

 skin of the posterior part of a triton, consisting mainly of the 

 trunk and of the two posterior members, this fragment, when 

 pinched, curves laterally as the intact animal would do to with- 

 draw the irritated point from the irritant body. 1 



Analogous facts have been observed by M. Ch. Robin on the 

 body of a decapitated man. He says : " The right arm of the 

 executed man, being extended obliquely on the side of the 

 trunk, the hand being 25 centimetres apart from the hip, I 

 scratched the skin of the breast with a scalpel, on a level with 

 the aureola of the mamma, to an extent of from 10 to 11 centi- 

 metres, without interfering with the subjacent muscles. We 

 saw immediately the great pectoral muscle, the biceps, the 

 anterior brachial muscle, and the muscles covering the epi- 

 trochlea contract successively and rapidly. The result was a 

 movement of approach of the whole arm toward the trunk, with 

 rotation of the arm on the inside, and demiflexion of the forearm 



1 Vulpian, Lemons sur la Physiologie Gten&rale et Compare du Syst&nw 

 Ncrveux, p. 417. 



