A HISTORY OF SCIENCE 



removed. The transition of food over the glottis and 

 along the middle and lower part of the pharynx de- 

 pends upon the reflex action : it can take place in ani- 

 mals from which the cerebrum has been removed or 

 the ninth pair of nerves divided; but it requires the 

 connection with the medulla oblongata to be pre- 

 served entirely; and the actual contact of some sub- 

 stance which may act as a stimulus: it is attended 

 by the accurate closure of the glottis and by the 

 contraction of the pharynx. The completion of 

 the act of deglutition is dependent upon the stim- 

 ulus immediately impressed upon the muscular fibre 

 of the oesophagus, and is the result of excited irrita- 

 bility. 



" However plain these observations may have made 

 the fact that there is a function of the nervous muscu- 

 lar system distinct from sensation, from the voluntary 

 and respiratory motions, and from irritability, it is 

 right, in every such inquiry as the present, that the 

 statements and reasonings should be made with the 

 experiment, as it were, actually before us. It has al- 

 ready been remarked that the voluntary and respira- 

 tory motions are spontaneous, not necessarily requir- 

 ing the agency of a stimulus. If, then, an animal can 

 be placed in such circumstances that such motions will 

 certainly not take place, the power of moving remain- 

 ing, it may be concluded that volition and the motive 

 influence of respiration are annihilated. Now this is 

 effected by removing the cerebrum and the medulla 

 oblongata. These facts are fully proved by the ex- 

 periments of Legallois and M. Flourens, and by sev- 

 eral which I proceed to detail, for the sake of the op- 



256 



