ON THE FUNCTIONS OF THE BRAIN. 73 



that of experiment by reproduction. This method, to some extent, 

 combines physiological analysis and synthesis, and enables us to estab- 

 lish by evidence and counter-evidence those relations which unite the 

 organ with the function in cerebral manifestations. When the brain 

 of the inferior animals is removed, the function of the organ is neces- 

 sarily suppressed; but the persistence of life in these beings allows the 

 brain to grow again, and, in proportion as the organ reproduces itself, 

 we observe its functions reappear. The like experiment succeeds in 

 the same way with superior animals, such as birds, in whom intelli- 

 gence is much more developed. For instance, when the cerebral lobes 

 of a pigeon have been removed, the animal at once loses its senses, 

 and the power of seeking its food. Yet if the animal is artificially 

 fed, it can survive, because its functions of nutrition continue unim- 

 paired so long as their special nervous centres are left unharmed. 

 Little by little the brain renews itself with its particular anatomical 

 elements, and in the degree in which this restoration takes place we 

 observe the animal's use of its senses, and its instincts and intelligence 

 return. Here, I repeat with emphasis, the experiment is complete : 

 there has been as it were both analysis and synthesis of the vital func- 

 tion, because the successive destruction of the different parts of the 

 brain has successively extinguished its different functional manifesta- 

 tions, and because the successive reproduction of the same parts has 

 caused the same manifestations to reappear. It is hardly necessary 

 to add that the same thing happens as to all the other parts of the 

 body which are susceptible of reproduction. 



Diseases, which are at bottom nothing but vital perturbations caused 

 by Nature instead of being produced by the hand of the physiologist, 

 affect the brain according to the usual laws of pathology ; that is to say, 

 by occasioning functional troubles which always correspond to the na- 

 ture and seat of the injury. In a word, the brain has its pathological 

 anatomy exactly as all the organs of the economy have, and the pa- 

 thology of the brain has its special series of symptoms, just as the 

 other oro-ans have theirs. In mental alienation we observe the most 

 remarkable disturbances of the reason, furnishing in their study a rich 

 mine for' the researches of the physiologist and the philosopher ; but 

 the various forms of lunacy or madness are nothing more than disturb- 

 ances of the normal function of the brain, and these alterations of func- 

 tion in the cerebral organ, as in all the rest, are combined with inva- 

 riable anatomical alterations. If, under many circumstances, these are 

 not yet understood, the blame must be laid wholly on the imperfection 

 of our means of investigation. Besides, do we not find that certain 

 poisons, such as opium and curare, paralyze the nerves and the brain, 

 without being able to discover any visible alteration in the nerve-sub- 

 stance ? Yet we are sure that such alterations exist ; for, to admit the 

 contrary, would be to admit an effect without a cause. "When the poi- 

 son has ceased to act, we find the mental disturbances disappear, and 



