

FRETS, THE INDEX CEPHALICUS. 531 
shorter (high index) equally occur the cases of growing narrower 
and longer (low index). 
These findings enhance, as I consider it, the significance of the 
index cephalicus and must effect that for other material!) similar 
computations are done. 
The results of inquiries with the index cephalicus. are often not 
clear, so that the investigator hesitates about the value of it. 
BENNINGTON and PEARSON write (1911, p. 306): „It would seem 
unusual to pass over the discussion of the cephalic indices and 
yet it is doubtful how far they are really indicative for important 
racial - differences. Thus the „Gaboon 1864” males and the Zulus 
differ but slightly in the height-length index, but the value in one 
case is produced by the head being unusually short and in the 
other case by its being abnormally high, relatively, to the majority 
of human races’. They accept the index 100 (B — H) Land call it 
the acroplatic index. I hope that my results will aid to simplify 
our conceptions of the index cephalicus. 
To conclude, the index cephalicus is a characteristic of which 
a racial and a sexual element is the basis and of which alter- 
ations take place according to the rule of compensational growth, 
in its effect varying for different capacities of head. 
This experience that a lower index is accompanied with a larger 
length of head (Boas, JOHANNSEN), expresses only part of the 
effect of the rule of compensational growth. The complete rule is: 
alterations of the form of head take place by an increase or decrease 
of each of the three dimensions of head in a correlated proportion. 
An increase of breadth is accompanied with a decrease of 
length and of height; a decrease of breadth on the other hand 
with an increase of the length and of the height. 
These effects of the compensational growth are not always the 
same: in the case of large heads, with an increase of breadth more a 
growing lower than a growing shorter is accompanied and in the 
case of small heads on the other hand more a growing shorter 
than a growing lower. 


1) For this study comes in the first place into consideration the material 
“ that in Biometrika was published of LEE (1901), FAWGETT (1902) MACDONELL 
(1904, 1905) and other contributors up to 1921. 

