78 
Proceedings of the Poyal Society of Edinburgh. [Sess. 
cells,” are largest in the upper part of the Rolandic area and diminish in 
size from above downwards. This observer also showed that the motor 
cells are arranged in groups. These observations have recently been con- 
firmed by Campbell,* working on the human and anthropoid brains, and he 
states further that the grouped arrangement of cells is found only in the 
areas forming motor centres for the limbs, while in the part of the ascend- 
ing frontal convolution at the level of the superior genu of the Rolandic 
fissure, from which movements of the body muscles are obtained, he finds 
the cells arranged in a solitary manner. According to Campbell, the size, 
configuration, and grouping of the giant cells vary in relation to the motor 
centres in which they are found, and the conclusions which he reaches by a 
consideration of their variations are in accord, mutatis mutandis, with the 
results which we have derived from the method of electrical excitation in 
monkeys when care is taken to isolate the areas in the manner before 
described.^ 
* Loc. cit. 
t The expenses of this investigation were defrayed by grants from the Moray Fund 
(University of Edinburgh) and the Carnegie Trust for the Universities of Scotland. 
{Issued separately May 6, 1907.) 
