CHAPTER 4 

 Blood Groups 



ABO Blood Groups 



It does not take profound knowledge of science to realize that no 

 two human beings, with the possible exception of identical twins, 

 are exactly alike. There are sometimes strong resemblances in families, 

 and sometimes even unrelated persons look enough alike to be mis- 

 taken one for the other by those who do not know them well, but 

 close associates are very seldom deceived. Features, voice, movements, 

 and modes of response nearly always distinguish each human being 

 from all others in the world. 



If we believe, and the belief hardly needs defending today, that 

 structural and functional differences between individuals, aside from 

 the effects of accidents resulting in scars or deformity and from 

 learned behavioral patterns, are due to underlying biochemical dif- 

 ferences, we should not be surprised to find that between different 

 individuals of the same species biochemical differences can also be 

 demonstrated. Surprisingly enough, this was done for the first time 

 at the beginning of the present century. Karl Landsteiner, then work- 

 ing in Vienna, discovered that not all normal human blood is alike. 

 Landsteiner and his pupils showed that human beings could be 

 classified into four groups on the basis of the reactions of their blood 

 with that of other normal individuals. This discovery made blood 

 transfusion a safe and practical procedure for the first time and had 

 great influence on the study of serological specificity. 



Landsteiner's discovery consisted of the observation that, when 

 the bloods of certain individuals were mixed, the red blood cor- 



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