440 M. A. VAN HERWERDEN 



B as a sign of east-European and Asiatic origin. But in our small fishertown 

 of Volendam (fig. 2) situated at the Zuiderzee, so well known to strangers by- 

 its typical population, not less than 22 per cent of the inhabitants belong to 

 bloodgroup B (random population). Another small inbreeding place in the 

 province of Zeeland, Westkapelle has 18 per cent B, percentages as we really 

 find them in the east-European population. Compare herewith the low. 

 percentage B of many other inbreeding communities. 



The columns next to Volendam (fig. 2) represent the distribution of blood- 

 groups in neighbouring communities in the same province, the percentage of 

 group B amounting only to 6.7 per cent. Figure 3 gives an idea of the differ- 

 ent percentage of group B in inbreeding communities in one of our eastern 

 provinces (province of Overijsel). Figure 4 represents the bloodgroup dis- 

 tribution in a rural community of the province of South Holland compared 

 with its surrounding places. 



It will be seen by further publications that our entire material collected 

 in the last 5 years points to the existence of considerable local variations as 

 to the bloodgroup distribution in our rural districts. Intermarriage during 

 centuries has created local populations, genetically different as a whole from 

 neighbouring populations. This is often reflected in the bloodgroups. 

 Haemagglutino genes are hereditary factors. When testing the bloodgroups 

 of inbreeding communities one may draw the conclusion that an unequal 

 distribution of other normal and abnormal traits exists in such neighbouring 

 rural places. It is not only tradition, but also hereditary difference which 

 gives a typical stamp to each of these small populations. 



