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somnolent reflex machine. The bird sits on its perch, 

 generally with its head turned back, as if sleeping. If a 

 sudden noise is made, if light is flashed in its eye, or if it is 

 touched, it flies off its perch and lights somewhere else. 

 But every stimulus produces the same result. Clapping 

 the hands and letting peas fall on the floor are both 

 obviously heard and 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 has 

 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 patted 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. 



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

 such loss of the so-called voluntary movements that all 

 other symptoms are masked. 



In the decerebrated animal different stimuli do not produce 

 distinctive reactions, but, with the cerebrum intact, there is 

 at least the possibility of small differences in the modes of 

 stimulation producing marked differences in the resulting 

 action. 



These resulting actions are in part at least determined by 

 (1) the previous training and education of the brain; for, 

 just as in the spinal cord channels of action are formed, so 

 in the cerebrum, if a given reaction once follows a given 

 stimulus, it will tend to follow it again, (a) This training is 

 in part hereditary. Each individual of a race is born with 

 well-established lines of action in the process of development, 

 and throughout life these inherited channels play an im- 

 portant part in determining the results of stimulation. 

 (b) But it is also largely acquired by the individual, since 

 the reception of each stimulus and the performance of a 



