246 COMPARATIVE PHYSIOLOGY OF THE BRAIN 



cerebral hemispheres starve unless they are fed. 

 Schrader came to the conclusion that this is due to a 

 disturbance of the motor innervation, for they are un- 

 able to swallow a pea placed in the front part of the 

 beak ; to be swallowed it must be placed well back 

 toward the throat. From the results of these experi- 

 ments on frogs, I believe that we might go one step 

 farther than Schrader and conclude that, in this case, 

 the tension is decreased in certain groups of muscles 

 which are necessary for taking food independently. 

 We shall again meet with such a decrease in the ten- 

 sion of certain muscles after lesion of the cerebral 

 hemispheres. This decrease in tension is, however, a 

 secondary effect of the operation on the remaining 

 srgmental tracts of the central nervous system, and is 

 not determined by loss of the cerebrum. It is very 

 probable too that if Schrader's experiments are con- 

 tinued birds may be found in which disturbances in 

 eating will not occur. 



3. The bold attempt to remove both hemispheres 

 entirely from a full-grown dog and then to keep it 

 alive not only for months but for years has been 

 attempted and carried on successfully by Goltz (6). 

 The results of his experiments in a few words are as 

 follows : In such a dog all those reactions in which the 

 associative memory plays a role are lacking perma- 

 nently, while the simple reactions that only depend on 

 inherited conditions remain just as in pigeons and in 

 other animals. 



The dog without cerebral hemispheres sleeps and 



