504 S. WALTER RANSON 



In nine adult white rats the skull was removed from over the 

 (lorso-latoral surface of the anterior half of the left cerebral 

 h(Muisi)liere and the underlying cortex was burned away. The 

 attempt was made to destroy all of the cortex on the upper and 

 lateral surfaces of the anterior half of the hemisphere without 

 injuring the underlying structure. 



After periods varying from 45 to 60 days, the rats were killed. 

 In each case the entire head was preserved in formalin. The 

 seventh cervical, eighth thoracic, and fifth linnbar segments of 

 the spinal cord were removed and prepared either by the Pal- 

 Weigert or the pyridine-silver technique. Four of the rats were 

 given a preliminary injection of ammoniated alcohol, as suggested 

 by Huber, before the cords were dissected out and the chosen 

 segments subjected to the pyridine-silver technique. This pre- 

 liminary injection of ammoniated alcohol through the arteries 

 decreases the shrinkage which results from fixing the tissue in 

 strong alcohol. The details of the method are given by Ranson 

 ('12) and Huber and Guild ('13). 



After the head was thoroughly hardened in formalin the 

 brain was dissected out and the extent of the lesion on the sur- 

 face of the brain carefully determined and recorded in notes 

 and drawings. The left hemisphere was then cut into four or 

 five sagittal sections and these were examined under the binocular 

 dissecting microscope to determine the depth of the lesion. 



The extent of the lesion varied somewhat. But in each case 

 the larger part of the upper surface of the anterior half of the 

 left hemisphere had been burned. In one case. No. 7, the lesion 

 was small and did not reach the mid-line, and in this case the 

 sections of the cord show that a considerable part of the motor 

 cortex had escaped injury. In the others with somewhat larger 

 lesions practically all of the motor cortex was destroyed, judging 

 from the completeness of the degeneration of the pyramidal 

 tract in the cord. 



In each case, except No. 7, the lesion extended to the lateral 

 ventricle which usually appeared as a thin-walled cyst through 

 which could be seen the corpus striatum and sometimes the cornu 

 ammonis and thalamus. So far as could be determined by a 



