294 SPECIAL PHYSIOLOGY. 



evidences of sensation, and of much muscular power. But when both 

 cerebral hemispheres are completely removed, a kind of stupor exists ; 

 the animal remains in one attitude, and seems incapable of originating 

 any independent movement. It still, however, retains the power of 

 reaction, or reflex motion, on the application of external stimuli; for 

 when the cerebral hemispheres of a pigeon are removed, leaving the 

 optic thalami and optic lobes, besides the reflex contraction of the iris 

 and closure of the eyelid, on the approach of a lighted candle, the 

 bird follows the light with the head ; so likewise, when the brain of a 

 rabbit, including the optic thalami, is removed, it will withdraw its leg 

 when it is pricked, and cry if its whiskers be pulled. But these 

 latter movements are not positive evidence even of conscious sensation, 

 much less of perception and will; they are, almost certainly, purely 

 reflex, performed on the same principle as the simpler reflex move- 

 ments, but possessing a more complex character; they are probably 

 entirely unaccompanied by perception, and even if they be associated 

 with any sensation, this is probably of a very feeble or obscure kind. 

 Even the pigeon, when deprived of the hemispheres only, as above 

 mentioned, though it may see objects, runs up against them, apparently 

 from loss of perception and memory. 



The cerebral hemispheres have been removed in birds, chiefly in pigeons 

 (Longet), which, by artificial feeding, have then been kept alive for months. 

 Birds so treated, sit still, as if asleep, with the neck retracted, the wings 

 closed, and resting on both feet. When pushed, or when the foot is pinched, 

 they seem to awake, to shake their body and feathers, open the eyes, advance 

 a step forwards, and then relapse into their state of slumber. If dropped in 

 the air, they spread out their wings, and even fly up, but strike against objects, 

 and soon fall to the ground, from which they do not attempt to rise again. 

 Sometimes they wake spontaneously, and prune their feathers. The eyes are 

 still sensible to light, the pupils contracting ; the eyelids are not closed at the 

 approach of a candle, but some signs of uneasiness are manifested, and the 

 bird follows the light by movements of the head. In a case observed by Mala- 

 corps, the pigeon was not affected by sudden exposure to strong light ; but it 

 appeared to seek out the light parts of a dark place ; and was readily roused 

 by slight noises. By Longet, however, noises were found to produce no effect, 

 but, when very loud, caused, at the most, the animal to start ; but this might 

 be simply due to the mechanical shock. If the toes be touched, the foot 

 is drawn away ; and on repeating the irritation, it may be withdrawn under 

 the wing, and the bird remain standing on one foot without loss of balance ; 

 if now, the other foot be irritated, it withdraws this, and puts out the opposite 

 one. If ammonia be held to the nose, the head is violently shaken, and the 

 bill is scratched with the foot. The bird can no longer pick its food ; when 

 this is placed in the bill it remains there ; but when put on the back of the 

 tongue, it is swallowed. 



Similar experiments have been made on quadrupeds, with corresponding 

 results, dogs no longer recognizing their master. All the phenomena seem to 

 show, that not only the movements, but even combinations of movements to 

 certain ends, occur after removal of the cerebrum ; the state of the animals, 

 however, is like that of dreaming, in which the acts are not accompanied by 

 distinct perceptions of external objects, though by an imperfect consciousness. 

 As regards sensory impressions, their condition is precisely similar, indicating 

 a feeble or imperfect persistence of conscious sensation. This result sufficiently 

 proves that the cerebral hemispheres are not the sole seats of consciousness, 

 if, indeed, they are at all concerned in mere sensation. The loss of conscious 

 power in such experiments, may not depend on any of it being, as it were, 

 resident in the hemispheres, and so lost with them, but on the shock to the 



