ix MID- AND INTER-BRAIN 501 



became the starting-point of all subsequent researches on the 

 cerebral centres down to the present day. 



According to the classical description of Flourens, the pigeon 

 deprived of its cerebral hemispheres is an animal condemned to 

 perpetual dreamless sleep. None of its senses are active ; it 

 remains motionless wherever it is placed; it never moves 

 spontaneously, and stays in the sleeping posture (Fig. 256). If 

 stimulated it seems to wake, opens its eyes, shakes its wings, 

 moves a little, and then relapses into slumber. If thrown into 

 the air it flies, but fails to avoid obstacles. It retains the capacity 

 of keeping its equilibrium both while standing, and in moving 

 when stimulated. It has completely lost the faculty of feeding 



FIG. 256. Pigeon deprived of its cerebral hemispheres in position described by Flourens. 

 (From a photograph by Dal ton.) 



by itself, so that it will starve in front of a heap of corn. It 

 shows no fear when any one approaches or threatens it, nor any 

 inclination for the other sex. It digests well when fed, and can 

 consequently survive for a long time. It digests sleeping; and 

 only makes a few aimless steps occasionally, owing to fatigue in 

 the legs. In short, the pigeon that has lost its fore-brain has lost 

 all its perceptions, all its instincts, all its intellectual faculties. 



But none of the physiologists who repeated Flourens' experi- 

 ment were able to convince themselves of the accuracy and 

 constancy of his description, nor that the ablation of the hemi- 

 spheres sufficed to produce total abolition of sensation in general, 

 and more particularly of vision and hearing. They found that 

 pigeons with no hemispheres were capable of avoiding obstacles 

 when they moved, of following the movements of a lighted candle 

 with their head, of starting violently at loud noises, as the report 

 of a pistol in a word, gave obvious signs of seeing and hearing. 



