110 K. S. LASHLEY AND S. I. FRANZ 



Retention was first tested on the second day after the opera- 

 tion. The animal moved about the floor of the restraining 

 cage for a few minutes, then settled down and remained motion- 

 less. The same thing happened on the next three days. On 

 the sixth day she became very spastic and during the tests 

 passed through a series of prolonged tonic spasms, exhibited in 

 arching of the back, retraction of the head, and gradual exten- 

 sion of the legs and feet so that she came to stand only on the 

 tips of her toes. This appeared after every rapid movement and 

 persisted for sometimes as much as two minutes. On the fol- 

 lowing day she was still more spastic and the spasms intervened 

 at every attempt to walk. On the ninth day after the opera- 

 tion she had partly recovered and succeeded in tripping the 

 plane four times. The average time for these four trials was: 

 to plane, 1117 seconds; to door, 70 seconds. On the following 

 days she again became spastic and showed no further improve- 

 ment in two weeks. 



Lesion (plate III, fig. 32). There is a transverse lesion com- 

 pletely separating the frontal poles of both hemispheres from 

 the remaining cortex, along a plane extending from the antero- 

 dorsal face of the hippocampus, through the forceps of the cor- 

 pus callosum to the base of the olfactory bulbs. There is a 

 separation of the left corpus striatum from the external capsule 

 and a partial invasion of the nucleus by large blood vessels. 

 There is a similar degeneration of the anterior end of the right 

 corpus striatum. 



After complete destruction of the frontal poles of both hemi- 

 spheres and. partial destruction of the cerebral nuclei this animal 

 gave no evidence of retention of the habit. 



Experiment 33. Operation on the frontal poles of the cere- 

 brum in a large female rat, 142 days old. She had been trained 

 for 120 trials on the inclined-plane box. The average time per 

 trial for the first five trials was: to plane, 2970 seconds; to door, 

 28 seconds. That for the last five trials was: to plane, 34 

 seconds; to door, 2.2 seconds. 



Retention was tested on the second day after the operation. 

 The animal was seemingly in good condition, ran about actively 



