334 NERVOUS SYSTEM. 



those of a bird operated on in the same manner, are ex- 

 clusively and directly due to a stimulation produced by 

 exterior excitations, or by interior inclinations, such as fa- 

 tigue, etc." l 



In view of the very great variety of movements that 

 occur in animals after removal of the cerebrum, it is quite 

 difficult to define precisely what movements are due to vol- 

 untary action depending upon some external or interior im- 

 pression, which are really reflex voluntary movements, and to 

 distinguish them from those which arise from a spontaneous 

 and, perhaps, an intelligent effort of the will. These points 

 have been so admirably described in a recent article, by 

 Onimus, that we quote his concluding summary : 



" As a summary, in the inferior animals, as- in the supe- 

 rior animals, the removal of the cerebral hemispheres does 

 not cause to disappear any of the movements that previous- 

 ly existed. Only, these movements assume certain peculiar 

 characters. In the first place, they are more regular, they 

 have the true normal type, for no psychical influence inter- 

 venes to modify them ; the locomotor apparatus is brought 

 into action without interferences, and one could almost say 

 that the ensemble of movements is then more normal than 

 in the normal condition. 



"In the second place, the movements executed take 

 place inevitably after certain excitations. It is a necessity 

 that the frog placed in water should swim, and that the 

 pigeon thrown into the air should fly. The physiologist 

 can then, at will, in an animal without the brain, determine 

 such and such an act, limit it, arrest it ; he can anticipate 

 the movements and affirm in advance that they will take 

 place under certain conditions, absolutely as the chemist 

 knows in advance the reactions that he will obtain in mix- 

 ing certain bodies. 



" Another peculiarity in the movements that take place, 

 when the cerebral lobes are removed, is their continuation 



1 VULPIAN, Systems nerveux, Paris, 1866, p. 680. 



