
THE INDEX CEPHALICUS 
by GAPA ERETS: 
Physician and Prosector to the Asylum Maasoord-Rotterdam. 
The investigation of the heredity of the shape of head, with which 
I have occupied myself for some years, placed me before the 
question, that has-been put in anthropology several times, what is 
the significance of the index cephalicus. 
By means of this investigation on heredity I found some charac- 
teristics of the index cephalicus, which I communicate here. At the 
same time I publish here some statistical data taken from my material. 
1.. STATISTICAL DATA. 
The material consists of the visitors calling on the inmates of : 
the asylum Maasoord of Rotterdam. By making numerous journeys to 
Rotterdam and other places, consequently somewhat in the manner 
of the fieldworkers, | have measured as completely as possible all 
the members of those families I found of interest for my work. Also 
a few other families have been inserted into the tables. All persons 
with a very rare exception are Dutch, most of them inhabitants of 
Z.-Holland and Zeeland. I believe that my material as far as the 
shape of the head is concerned may be regarded as normal. Of course 
deformities of the head are not included in the material. 
The total number of observations amounts to 3600, 1545 men 
and 2057 women. From these 3475 observations are gathered in 
the tables A- E. All measurements are done by myself with excep- 
tion of those of fam. 324, which nearly all have been done bythe 
amanuensis of the laboratory. The calculations of the index have 
all been done by myself. For the statistical calculations I had valuated 
help. Nearly all have been done once by myself; moreover for 
control and because the increase of the material within the 
Genetica IV. 31 
