332 NERVOUS SYSTEM. 



We will now proceed to describe, as accurately as possi- 

 ble, the condition of an animal after complete extirpation of 

 the cerebrum, as observed in numerous experiments that we 

 have ourselves made on this subject, premising the statement 

 that these are merely repetitions of observations made by 

 other physiologists. 



A pigeon, in a perfectly normal condition, is deprived 

 of the hemispheres, by removing the calvarium and carefully 

 scooping out the parts with the handle of a scalpel. This 

 operation is usually not difficult, and the haemorrhage is soon 

 arrested spontaneously. The slit in the scalp is closed with 

 sutures, and the animal is set at liberty. 



The appearance of the animal after this mutilation is 

 peculiar and characteristic. There immediately supervenes 

 a condition of stupor. There is usually no attempt at move- 

 ment, and, though the pigeon stands upon its feet, the head 

 is almost buried in the feathers of the neck, the eyes are 

 closed, and the attitude is one of absolute indifference to 

 surrounding conditions. The muscles seem to act with just 

 sufficient vigor to maintain the standing position. If we 

 pinch one of the toes, or grasp the beak, there is evident 

 sensation, and a persistent and more or less vigorous effort 

 is made to release the part. It is sufficiently evident, from 

 these and other tests, that sensation and the power of volun- 

 tary motion are retained ; but as soon as the animal is left 

 quiet, it relapses into its stupid condition, makes no effort 

 to escape, and apparently loses immediately all recollection 

 of having been disturbed. The irritation has evidently pro- 

 duced a sensation of discomfort, and has given rise to a 

 voluntary muscular effort ; but there has been no idea of 

 danger, nor an intelligent effort to avoid a repetition of the 

 disagreeable or painful impression. 



It is easy to demonstrate, by experiments such as we 

 have just alluded to, that the animal sees and hears, and 

 retains the sense of taste ; but it connects no idea with any 

 thing seen, and the report of a pistol, which, under natural 



