704 PHYSIOLOGY. 



ideas regarding his own personality, and his relations to what is tak- 

 ing place inside and outside his body. He considers himself enor- 

 mously wealthy, or a genius, or he may fail to recognize his own sur- 

 roundings, and perform acts not reconcilable; in other words, he is 

 like one with paresis. When disease attacks the posterior associa- 

 tion centers he is unable to name correctly objects which he can 

 touch and see, or, if both centers are affected, he may not at all 

 recognize the nature of these objects, so that he loses the power of 

 forming intelligent conceptions of the world around him. He is 

 bankrupt in ideas, although his affections may not be altered. In 

 other words, he has what is called mind-blindness. The posterior 

 association center is highly developed in musicians. 



PHENOMENA FOLLOWING THE DESTRUCTION OF ONE OR 

 BOTH OF THE CEREBRAL HEMISPHERES. 



Ablation of the cerebral hemispheres is generally performed in 

 frogs or fowls, who seem to endure the operation sufficiently well. 

 Mammals easily succumb. 



The skin of the head being cut and the thin cap of the skull 

 removed, the brain is reached. The incision of the meninges is pain- 

 ful, but, after gradually removing the mass of the hemispheres from 

 above downward, the bird shows itself indifferent. In fact, it be- 

 comes more stupid and apathetic as more of the cerebral tissue is 

 removed. When the removal of the hemispheres is completed without 

 injuring the peduncular system, with its ganglia, and the haemorrhage 

 stopped as well as possible, the bird remains in a sleepy state. It 

 has a tendency to bury its head and close its eyes ; it breathes slowly, 

 but does not walk away. 



Under stimulation the bird reopens its eyes, raises its head, takes 

 a few steps, then suddenly returns to its former position. 



The bird, having recovered from its traumatism, the following 

 phenomena are observed within a few days: The bird has become 

 an automaton. It does not eat, so that it becomes necessary to put the 

 food into its mouth. It moves not at all of its own volition ; if pur- 

 sued it takes some steps; its pupils contract under the influence of 

 the light; it cries or tries to flee when the skin is irritated. It is 

 startled by loud noises. For the rest there are no longer voluntary 

 movements, and the few movements observed are aroused by external 

 excitement, or some internal need. The movements are rubbing the 

 skin with the beak, scratching the head with the foot, etc. 



