80 K. S. LASHLEY AND S. I. FRANZ 



the right to the base of the lobe behind the olfactory bulb. 

 Practically all the cortex of both hemispheres lying in front of 

 the knee of the corpus callosum is destroyed by the lesion. 



Experiment 2 (page 8). Partial retention. Errors: learning 

 8, retention 2. 



Lesion. Not enough sections of the brain were preserved for 

 an accurate determination of the extent of injury. Apparently 

 the lesion was superficial, extending over the antero-dorsal sur- 

 face of the frontal poles. 



Experiment 3 (page 9). Partial retention. Errors: learning 

 2, retention 4. Secondary evidence of retention. 



Lesion (plate II, fig. 3). The brain was imperfectly sectioned. 

 Right hemisphere. There is a transverse section of the hemi- 

 sphere just in front of the forceps of the corpus callosum, extend- 

 ing from the inner margin of the mesial cortex through the 

 lateral cortex. Left hemisphere. The lesion is similar to that 

 on the right but involves the mesial cortex as well. 



The posterior extent of the lesion could not be determined 

 accurately. The destruction was certainly not less than that 

 shown in the figure. 



Experiment 4 (page 9). Partial retention. Errors: learning 

 21, retention 2. 



Lesion (plate II, fig. 4). Right hemisphere. There is a 

 complete transection of the anterior pole in a vertical plane 

 passing through the knee of the corpus callosum. Left hemi- 

 sphere. The cut is in the same plane as that on the right but 

 penetrates only from the mesial surface to the external capsule 

 and ventrad to the fibers of the peduncle. 



Experiment 5 (page 10). Perfect retention. Errors: learn- 

 ing 19, retention 2. 



Lesion (plate II, fig. 5). Right hemisphere. There is a 

 small injury on the mesial surface above the knee of the corpus 

 callosum. Left hemisphere. There is a small cylindrical cyst 

 extending from the dorsal cortex through the knee of the corpus 

 callosum and the cerebral peduncle, severing the fibers coming 

 from the frontal pole. 



Experiment 6 (page 10). Perfect retention. Errors: learn- 

 ing 7, retention 0. 



