242 ROBERT S. ELLIS 



Differences between right and left hemispheres. A glance at the 

 table shows that in most cases there is a considerable difference 

 between the values for the right and left hemispheres. In three 

 cases the values for the- right hemispheres are larger, while in 

 one case the value for the left is the larger. Unfortunately, it is 

 not known whether these cases were right or left handed, and it 

 is consequently impossible to show here a positive correlation 

 between a greater number of cells and superior unilateral skill. 

 As a suggestion, however, it is not improbable that we have here 

 three right-handed individuals and one left-handed. In any 

 case it may be noted that the differences between the right and 

 left hemispheres are greatest in areas 3 and 4, the supposed arm 

 and hand areas, and that they are least in area 2, the neck area. 

 On purely a priori grounds this is what is to be expected if there 

 is a correlation between number of cells and fineness of muscular 

 coordination. The greatest difference between the right aixl left 

 hemispheres should be in the hand and arm areas, because it is 

 in the two hands that there is normally the greatest difference in 

 motor skill. In the neck area there is obviously less reason for 

 expecting one side to be more developed than the other. How- 

 ever, further studies must be made here on cerebella from cases 

 with known histories before this question can be answered with 

 any assurance of correctness. 



SUBNORMAL CASES 



In order to compare the relative frequency of Purkinje cells 

 in the cerebella of subnormal individuals, the histories of which 

 have been given on page 232 f, with normal ones, counts have 

 been made on areas 1, 3, 4, and 6 of the right hemisphere and 

 on areas 3 and 4 of the left hemisphere. These results are 

 presented in table 2. 



It is obvious at a glance that in this group of mental defectives 

 the number of Purkinje cells is notably deficient. The con- 

 stancy of the results and the wide difference between the values 

 for the normal and those for the defective cerebella as shown 

 by' the fact that the latter are only 63 to 78 per cent of the 

 former make it impossible to assume that accident, chance, or 



