LASHLEY— CEREBRAL FUNCTION 257 



Retention Tests. — The animals all showed marked paralysis after 

 operation. This cleared up gradually, and the retention tests were 

 given about two months after the operation. (Numbers 1 and 3, v.i., 

 recovered somewhat more quickly than is usually the case when the 

 lesion is restricted to one hemisphere.) In the postoperative retention 

 tests, the animals were placed singly in the large cage with each of the 

 latch boxes in turn. The time required to open the boxes was noted, 

 and the methods were recorded in detail for comparison with methods 

 employed in learning and in the preliminary retention tests. 



Verification of Lesions. — When the tests were completed, the opera- 

 tive fields were again exposed and explored by electrical stimulation. 

 Excitable points found were mapped. The brains were then removed, 

 fixed in 10 per cent, formaldehyd. and sketches made under a camera 

 lucida. Serial sections of the region of the lesions were then prepared. 

 Camera drawings of these were made and the lesions reconstructed 

 from them. 



PROTOCOLS 



Number 1. — This was a small male cebus, trained on the crank box, pull box 

 and hasp box. The skull was trephined and opened on both sides in front of 

 the precentral gyrus. The openings were extended backward to the fissure of 

 Rolando. The leg, arm and face areas were located by electrical stimulation 

 and destroyed by cautery. Cauterization extended beyond the stimulable area 

 except in the median line. The wound was covered with mica and closed. 



On the following day, there was a partial paralysis of both sides with great 

 spasticity. Coordinated walking movements were possible, but there was great 

 weakness of the legs. The arms were extended toward food. He could not 

 grasp with his left hand. Partial grasping with the right hand appeared, but 

 there was inability to raise food to the mouth. He recognized a banana, and 

 made efforts to grasp it. The arms were usually hyperextended. 



Four days later, he moved clumsily, his arms and legs spread out frequently, 

 letting him fall prone. He grasped with his right hand, but was unable to hold 

 food or lift it to his mouth. He ate by thrusting his mouth against the bread. 

 He was well oriented in the room. Two weeks before operation he had learned 

 to slip out of the crack as the door was opened and to run into an adjoining 

 room. He did this twice on the fourth day. He had a tendency to stay near a 

 cage containing other monkeys and to hide under it when pursued. There was 

 marked tremor after slight effort. 



Ten days after operation, he stood and walked without falling, fumbled in 

 grasping, but was able to hold food in the right hand or to lift it to his mouth. 



Thirty-five days after operation, he climbed and ran accurately, picked up 

 small pieces of banana with the right hand without noticeable clumsiness, and 

 made quick movements in efforts to catch flies. Retention of the problem-box 

 habits was tested at this time. 



The average time per trial in each day's practice (five trials daily) is given 

 in Table 1 for each of the problem-boxes. This is followed by the average time 

 per trial on each day of the preliminary retention tests, and similarly for the 

 postoperative retention tests. 



