726 WITHOUT CEREBRAL HEMISPHERES. [BOOK in. 



together utterly heedless of a carrot or cabbage-leaf placed just 

 before its nose, though if a morsel be placed within its mouth 

 it at once begins to eat. When stirred it will with ease and 

 steadiness run or leap forward; and obstacles in its course are 

 very frequently, with more or less success, avoided. In some 

 cases the animal (rat) has been described as following by move- 

 ments of the head a bright light held in front of it (provided 

 that the optic nerves and tracts have not been injured during 

 the operation), as starting when a shrill and loud noise is made 

 near it, and as crying when pinched, often with a long and 

 seemingly plaintive scream. So plaintive is the cry which it 

 thus gives forth as to suggest to the observer the existence of 

 passion ; this, however, is probably a wrong interpretation of a 

 vocal action; the cry appears plaintive simply because, in con- 

 sequence of the completeness of the reflex nervous' machinery 

 and the absence of the usual restraints, it is prolonged. 



Without insisting too much on such results as these, and 

 allowing full weight to the objection which may be urged, that 

 in some of these cases parts of the cerebral hemispheres sur- 

 rounding the optic thalami were left, there still remains ade- 

 quate evidence to shew that a mammal such as a rabbit, in the 

 same way as a frog and a bird, may in the complete or all but 

 complete absence of the cerebral hemispheres maintain a natural 

 posture, free from all signs of disturbance of equilibrium, and 

 is able to carry out with success, at all events all the usual and 

 common bodily movements. And as in the bird and frog, the 

 evidence also shews that these movements not only may be 

 started by, but in their carrying out are guided by and coordi- 

 nated by afferent impulses along afferent nerves, including 

 those of the special senses. But in the case of the rabbit it is 

 even still clearer than in the case of the bird that the effects of 

 these afferent impulses are different from those which result 

 when the impulses gain access to an intact brain. The move- 

 ments of the animal seem guided by impressions made on its 

 retina, as well as on other sensory nerves; we may perhaps 

 speak of the animal as the subject of sensations; but there is 

 no satisfactory evidence that it possesses either visual or other 

 perceptions, or that the sensations which it experiences give 

 rise to ideas. Its avoidance of objects depends not so much on 

 the form of these as on their interference with light. No image, 

 whether pleasant or terrible, whether of food or of an enemy, 

 produces an effect on it, other than that of an object reflecting 

 more or less light. And we may infer that it lacks the posses- 

 sion of an intelligent will. But it must always be remembered 

 that some of the phenomena are due to the operation producing 

 other results than the mere absence of the part removed. We 

 must bear in mind that in all the above experiments while the 

 positive phenomena, the things which the animal continues able 



