190 JOSEPH DUERSON STOUT 



lighter lines. The areas for movements of the body segments 

 are dealt with as if they extended in straight lines mostly, but 

 in this respect the figures are necessarily diagrammatic. 



The reproduced illustrations are slightly larger than the 

 original brains, and in the figures the fissural variations are 

 shown. 



Figures 9 to 12 show the respective distributions in cats 8, 9, 

 10 and 12 of the areas of the right hemispheres for the four ana- 

 tomical groups which have been made, and figures 13 to 16 give 

 similar results for the left hemisphere of cats 10, 11, 14 and 15 

 respectively. Figure 4 shows the total superficial area ob- 

 tained by the summation of the areas in all animals. In each 

 of the figures 9 to 16 are shown the distributions of the fields for 

 head and neck, fore limb, hind limb and trunk and tail. The 

 results,, which are graphically represented, show a great amount 

 of variation in location of the motor responsive cortex in the hemi- 

 spheres of different animals. For one animal, cat 10, of which 

 both hemispheres were investigated, a similar deviation was 

 found (compare figs. 11 and 13). These variations are ap- 

 parently greater than the gross anatomical variations in fissural 

 arrangement, and the great differences in the relative sizes and 

 overlappings of areas are readily noted. 



The figures representing the combined fields (figs. 4 to 8) are 

 not to be interpreted as the average field, but solely as the widest 

 distribution of areas in which stimuli were found to result in 

 movement in the animals which were sufficiently investigated. 

 The compactness cr solidity of the areas for the fore and hind 

 limbs is in marked contrast with the wide and isolated distribu- 

 tion of the areas for the head and neck and the trunk and tail. 

 In the individual hemispheres similar diffusion or separation of 

 the areas was sometimes found, as is shown in figures 10, 12, 

 15, and 16. 



Considering the field for the head and neck, on the right cor- 

 tices, it is seen that in cat 8, figure 9, the field is slightly external 

 to and mainly anterior to the outer end of the crucial sulcus. 

 In cat 9, figure 10, it is again external to the end of the crucial 

 sulcus, but not entirely posterior to it. In cat 10, figure 11, it 



