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BLOOD  STAINS                                                          99

These figures vary widely in different countries as indicated by the fol-
lowing relative frequency of the blood groups in England obtained by analysis
of 1,073 unrelated persons 2G : 

Group                        I          Group           ,          Group                      Group

O                            I              A                            B                            AB

Per cent 46.0
	Per cent 42.0
	l Per cent
	Per cent 2.7

Recent research has shown that the red blood corpuscles of certain
individuals contain the Rhesus factor or Rh haemogen (hsernagglutinogen),
and are agglutinated by the antirhesus sera obtained by injecting the red
blood corpuscles of a rhesus monkey into rabbits or guineapigs. Such indi-
viduals are said to be Rh positive, while others whose red blood corpuscles
lack the Rh haemogen are known as Rh negative, and do not normally have
Rh haemagglutinins in their sera. These Rh haemagglutinins are liable to
be formed in the sera of Rh negative individuals by the introduction of Rh
hsemogen in their circulation through transfusion of Rh positive blood, or
by the passage through the placental circulation in pregnant women of the
foetal blood containing the Rh hsernogen inherited by the foetus from its
Rh positive father. These two types of blood are independent of the four
blood groups and the M and N blood types. The Rh haemogen is present
at birth and is inherited as a simple Mendelian dominant by a pair of
allelomorphic genes, Rh and rh. The Rh type is further sub-divided into
Rhi and Rh2 and resembles the sub-groups AI and A2 in hereditary trans-

It is now determined that the Rhesus factor (Rh hsemogen) is not a
single antigen, but a complex body composed of six antigens, which are
known as C, c, D, d, E and e. A chromosome, which contains three sites
carries a member of each pair of these antigens. Eight possible combinations
may thus occur.

The normal distribution of the Rh types in different races is given
below in a tabular form : 

Races                                       Rh positive type      |     Rh negative type

	Per cent
	r I            Per cent

Indians in Calcutta27
	j                10.0

Indians in Bombay28 English People29 White Americans30
	98.0 84,6 85.0
	1                   2.0 1                 15.4 15.0

Some more hsemogens (antigens), such as S, P, Q, G3 and H, have
been found in the human red blood cells. Of these the first two, viz. S and
P have been studied in detail.

The S antigen is demonstrable with isoimmune human serums, is asso-
ciated with the MN system and produces three more types, viz. MS, NS

26.    G. L. Taylor and E. W. Ikin, Brit. Med. Jour., May 20, 1939, p. 1,027.

27.    Greval and Chowdhury, Jour. Ind. Med. Res., 1943, XIII, p. 65.

28.   Khanolkar and Sangvi, Nature, April 7, 1945, Vol. 155, No. 3936, p. 427.

29.    Hoare, Brit. Med. Jour., Sep. 4, 1943, p. 297.

30.    Landsteiner and Wiener, Proc. Soc. Exp. BioL and Med., 1940, XI JIT, p, 223,