CEREBRUM 



185 



both produce a start, but the bird makes no endeavour to 

 secure the peas, as it would do in the normal state. 



(3) In the dog, by a succession of operations, Goltz 

 removed the greater part of the cerebral cortex without 

 causing paralysis of the muscles. The animal became dull 

 and listless, and did not take food unless it was given to it. 

 It showed no sign of recognising persons or other dogs, and 

 did not respond in the usual way when petted or spoken to. 

 But it snapped when pinched, shut its eyes and turned its 

 head away from a bright light, and shook its ears at a loud 

 sound. It did not sit still, but walked constantly to and fro 

 when awake. It slept very heavily. In fact all the responses 

 of the animal might be classed as reflex responses to imme- 

 diate excitation. 



FIG. 96. --A, pigeon with the cerebellum destroyed to show struggle to main- 

 tain the balance ; B, pigeon with cerebrum removed to show balance 

 maintained, but the animal reduced to a somnolent condition. 



(4) In monkeys, removal of the cerebral cortex leads to 

 such loss of the so-called voluntary movements that all 

 other symptoms are masked. 



After section through the crura cerebri, so as to remove the 

 influence of the cerebrum, a condition of increased tonic con- 

 traction of the muscles occurs known as deeerebration rigidity. 

 This appears to be due to the uncontrolled action of the 

 kinsesthetic and labyrinthine mechanisms acting through the 

 cerebellum. It is often well seen in old cases of apoplexy 

 where a haemorrhage has cut the fibres coming down from the 

 cerebrum. 



By destroying the cerebrum the animal is deprived of a 

 most important mechanism for the co-ordination of incoming 

 impressions from the peripherally-placed receptors with the 

 combinations of muscular movements by which appropriate 



