ihe NAOKI SUGITA 
The results obtained by me (Sugita, 718 c) in the albino and the 
Norway rats have been also entered. 
IX. THE SIZE OF THE LARGEST CORTICAL CELLS IN MAN AND 
SOME OTHER MAMMALS 
From table 12 we can draw only very general conclusions as to 
the significance of the size of the largest cortical cells. The giant 
Betz cells even in man vary rather widely in size according to the 
different authors, probably owing largely to the different tech- 
nical methods used, as has been pointed out repeatedly in the 
course of this paper. 
From time to time attempts have been made to formulate a 
general interpretation of the size of the Betz cells and of the 
nerve cells in general. From the examination of table 12, it is 
seen that the values for the mean diameters do not, except in 
the very most general way, follow the size of the animal, but 
that the Felidae, even the cat, stand high in the series. 
We are not able to contribute any general explanation for the 
size of these cells, although it may not be out of place to repeat 
that in the Norway rat with the heavier brain these cells are 
larger than in the albino rat with the lighter brain (Sugita, 
18 ¢), and so will merely call attention to the various authors 
who have had something to say in the matter: Lewis (’79), 
Hughlings Jackson (’90), Schwalbe (’81), Barratt (01), Dunn 
(00, ’02), Herrick (’02), Donaldson (03), Campbell (’05), 
Boughton (’06), Johnston (708), and Kidd (15). 
X. SUMMARY 
1. In the present paper I have attempted to compare my con- 
clusions regarding the development of the cortical elements in the 
brains of the albino and the Norway rats with the corresponding 
changes in other mammals. The data used for these comparisons 
were taken from various sources, but the comparisons are in 
many instances hampered by differences in technique or the 
lack of essential information. 
2. The relations of the cortical thickness at different locali- 
