Functions of the Cerebrum. 665 



These demonstrations, we have been in the habit of saying, indicate 

 states of the mind, but it is obvious this does not follow. They indi- 

 cate physical states, and physical states alone are demonstrably sufficient 

 to produce the phenomena which we are in the habit of calling mental. 

 Animals from which the cerebrum has been taken, may still exhibit, 

 when subjected to the proper stimulations, all the expressions of emo- 

 tion which would be due to follow these if the animal had its cerebral 

 hemispheres and its consciousness. < ' They start at sounds, flinch at 

 light thrown in their eyes, or even direct their movements in relation 

 with retinal impressions ; respond by movements expressive of disgust 

 or discomfort at unpleasant nasal or gustatory stimuli, and make the 

 most varied reactions to stimulation of the nerves of common sensation. 

 Frogs croak as if from pleasure when their backs are gently stroked, 

 and rabbits scream piteously, and exhibit the various signs of agitation 

 characteristic of intense pain, if their toes are pinched or any sensory 

 nerve severely stimulated." (Ferrier. ) Nevertheless there is obviously 

 no pain, feeling or. consciousness whatever. These same expressions, 

 when they happen during conditions of consciousness, are still reflex, 

 and are performed without the co-operation of the will, and often in 

 spite of it. 



' ' The phenomena observed in animals deprived of their cerebral 

 hemispheres, are in all respects analogous to those observed in human 

 beings under the influence of chloroform. Chloroform, as proved by 

 actual experiment, first annihilates the excitability of the hemispheres, 

 a condition coinciding with the abolition of consciousness, but the mes- 

 encephalic and lower centers retain their excitability long after this 

 point has been reached. Hence, impressions, which, under normal con- 

 ditions would excite pain as well as groans, cries, and the other phy- 

 sical expressions of pain, now merety excite the physical manifestations 

 without any painful sensation proper. " ( Ferrier.) 



This is important as showing beyond controversy that the centers 

 governing physical demonstrations of emotion, are set going by stimula- 

 tions coming direct from the environment through the nerves of sensa- 

 tion, without the co-operation of the will and without involving the cere- 

 bral organs or consciousness in any way. But we know that these very 

 same demonstrations of emotion, through the same centers and reaching 

 the same muscles by way of the same efferent nerves, are also set in 

 motion by stimuli which do originate immediately in the cerebrum 

 among the organs of the internal senses. We are bound to conclude 

 first, that the stimulation which comes from the cerebral centers is of 

 the same nature as that which comes from the peripheral senses, and we 

 are confirmed in the position that the cerebral or internal senses are only 

 elaborated forms of the peripheral senses, and the stimulations pro- 



