RONALD E. MYERS 



493 



moderate type lesion, removal of the striate plus adjoining cortex generally 

 believed to be visual in import; and the maximal type lesion, removal of 

 all cortex exclusive of the anterior pole containing the sensorimotor 

 cortex. The deep-lying ganglionic masses as well as piriform cortex were 

 left undamaged by these procedures. 



After a post-operative recovery period of at least 12 days, performance 

 levels were tested for the first time through the opposite untrained eye. 

 The results obtained with discrimination Ill-ab are given in Table III and 

 with discrimination Il-ab in Table IV. If the results of Table III arc con- 

 sidered together regardless of lesion type represented, about half revealed 

 high level performance on the first day of testing and the remainder a high 

 level performance by the second day. Fig. 7 represents in graphic form 

 performance of two of these cats showing greater (C/;r) and lesser {Alyii) 



Table IV 



PERFORMANCE WITH UNTRAINED EYE ON DISCRIMINATION II-AB AFTER 

 DESTRUCTION OF CONTRALATERAL 'tRAINED' CORTEX 



degrees of interocular transfer. The general outcome bespeaks good recall 

 on the tests through the untrained eye following cortical extirpation 

 from the contralaterally lying 'trained' hemisphere. However, if this 

 outcome is closely compared to that obtained on transfer testing after 

 chiasma-section alone (without the superimposed cortical removal) it is 

 clear that the cortical removal resulted in some decrement in contralateral 

 recall (contrast discrimination Ill-ab, Table I with discrimination Ill-ab, 

 Table III). 



The numbers of cats included in this study trained on the more difficult 

 discrimination Il-ab have been few but results obtained have been con- 

 sistent. Reference to Table IV shows that in all instances performance on 

 the first day of testing did not differ greatly from chance and that through 

 subsequent days, performances only gradually improved. Fig. 8 represents 



