ISOHEM AGGLUTININS 173 



children inherit it. (4) When a particular substance is absent 

 from both parents, no child ever has it." 



Racial Distribution of Groups. — In 1919 L. and H. Hirschfeld 

 published the results of their studies of the distribution of human 

 blood groups among- sixteen nationalities including over eight 

 thousand individuals. The data were obtained during the World 

 War while they were serving as army physicians on the Balkan 

 Front. They observed a significant difference in frequency of 

 occurrence of the agglutinogens among different races. Since 

 then, many additional studies have been made. 



Racial Types. — The data obtained by the Hirschfelds indicate 

 that the nationalities may be grouped into three types (see 

 Snyder, 1929, p. IIS) the European, Intermediate and Asio-AI'rican 

 types. In the European type, which is made up of the English, 

 French, Italians, Oermans, Austrians, Serbians, filreeks and Bul- 

 garians, the frecpiency of the A factor is quite constant, varying 

 from 41.8 in the Italians to 48 in the Germans. On the other 

 hand, the B factor shows a progressive increase from 10.2 for 

 the English to 20.4 for the Bulgarians. In the Intermediate 

 group, composed of Arabs, Turks, Russians and Jews, the fre- 

 quency of the A factor still exceeds that for B, but they are 

 noticeably closer together. The Asio-African type is composed 

 of the Madagascans, Senegalese, Annamese and natives of India. 

 In this group the frequency of the B factor is equal to or defi- 

 nitely greater than that for the A factor. In these determina- 

 tions, the data for the A factor include A and AB, while those 

 for the B factor include both B and AB. Ottenberg (1928) has 

 also given an excellent summary jof the frequency of blood 

 groups in different populations.* 



Frequency in Different Populations. — Apparently the fre- 

 quency of the group varies between wide limits. The Chinese 

 show a frequency of 30 ; the Russians, 40.2 ; Germans, 40 ; French, 

 43.2; English, 46.4; Australian aborigines, 51; and the American 

 Indians, 77.7 to 91.3 according to different investigators. 



High Incidence of Group in the American Indian. — The 

 American Indians have been studied by Coca and Deibert (1923), 

 Snyder (1926) and Nigg (1926). It is interesting to note that 

 all three studies have shown a high incidence for group and a 



*It is interesting- to note reported variation in the incidence of the N factor. 

 Vibeke Fabricius-Hansen finds it lower in the Greenland Eskimos and American 

 Indians than in other peoples, J. Immunol. 38: 40.5. 1940. 



