670 THE CEREBKUM 



fed and properly attended to. In fact, its initial lethargy is partially 

 compensated for in time, owing to the gradual development in the lower 

 centers of certain activities previously suppressed. 



The removal of the cerebral cortex in mammals presents several 

 technical difficulties and is attended by certain motor and sensory 

 defects which do not permit of a precise analysis. Still, it is easily 

 noted that this operation does not destroy the ordinary spinal and basal 

 reflexes and does not lead to a complete disarrangement of the motor 

 functions. This is true not only of rabbits, guinea pigs, and cats,^ 

 but also of dogs. Directly after the operation, these animals showed 

 a spastic rigidity of their extremities, the so-called decerebrate 

 rigidity, 2 as well as an extensor tonus and an upward deviation of the 

 head, or opisthotonos. These symptoms disappeared in the course 

 of a few days, whereupon the animal was capable of making relatively 

 precise muscular movements. 



The dogs of Goltz^ were operated on at intervals of several months, 

 a part of the cerebrum being removed each time. They were kept 

 for 51 and 92 days and one 'for 18 months. On autopsy it was found 

 that they had retained small portions of the striate body, optic thala- 

 mus and uncus. All these parts, however, were soft and atrophic and 

 in all probability functionally useless. The animals began to move 

 about within a few days after the operation and even walked across 

 inclined planes. They rested by assuming the usual position, but 

 could not be kept in a normal nutritive condition, in spite of the fact 

 that they were rather overfed. They reacted to sensory stimuli 

 by snarling, barking and the erection of the ears, but not in a way to 

 display recognition or to effect an intelligent motor response. Their 

 spinal reflexes remained normal. The animal which was kept longest, 

 finally acquired the power of taking food without being helped, 

 although it had to be held directly under its nose. Food with a dis- 

 agreeable taste was not swallowed. In general, therefore, these ani- 

 mals displayed the same defects as the birds, reptilia and amphibia, 

 namely, a loss of understanding and memory which made willful and 

 purposeful motor responses impossible. Only the simple reflexes were 

 retained, namely, reactions which do not involve complex associations. 

 The condition of these animals was one of general imbecihty. 



It has previously been emphasized that the development of the 

 cerebral hemispheres in the higher animals leads to the gradual 

 transfer of at least a part of the motor processes to this realm. This 

 implies that they are finally subjugated to the activities of the cortex. 

 As this higher control must, of course, be most complete in the apes and 

 man, it may be inferred that the destruction of parts of their cere- 

 brum must give rise to symptoms which are much more intense and 

 lasting than those previously noted in the case of birds, reptilia and 



1 Probst, Jahrb. fiir Psych, und Neurologie, 1904. 



2 Sherrington, Phil. Transactions, London, 1896. 



3 Pfluger's Archiv, iii, 1892, 570. 



