504 ANNUAL REPORT SillTHSONIAN INSTITUTION, 1937 



that is to say, in blood that is kept in glass vessels, and in vivo, in a 

 living organism; but their circulation is seriously impeded and very 

 grave accidents may be produced. 



The idea of blood-transfusion, of injecting foreign blood into a 

 subject weakened by excessive bleeding, is not a new one; we know 

 of undoubted instances occurring as early as the fifteenth century: 

 That of Pope Innocent VIII, for example. The results of these early 

 transfusions, made mostly with the blood of heifers or lambs, were 

 so disastrous that in the seventeenth century the operation was 

 made illegal by an act of parliament passed in Paris. The cause 

 of these failures was partly discovered in 1874, when Landois showed 

 that the serum of an animal of one species agglutinates the red cor- 

 puscles of animals of other species; that is to say, that if one mixes 

 the blood of two animals of different species, there ensues a general 

 clumping of their corpuscles: That has been called hetero-agglutina- 

 tion. At that date it was thought that agglutination only took place 

 between the bloods of diflferent species. Accordmgly transfusions 

 were then made again but only with human blood; the results were 

 good in certain cases but still disastrous in others. That was the 

 state of affairs when, about 1900, several doctors observed fortuitously 

 that the serum of certain sick people agglutinated the red corpuscles 

 of healthy patients. This phenomenon, which was called iso-agglu- 

 tination, was at first regarded as indicating a pathological condition; 

 but researches were continued and Landsteiner proved that, when 

 the blood of two perfectly healthy people was mLxed, agglutination 

 was produced or not accordmg to the patients who were the subject 

 of the experiment. He concluded from his experiments, on the one 

 hand that iso-agglutination can exist in a normal human being, on 

 the other hand that the iso-agglutinating properties are not the same 

 in all human beings, and that these should, from this point of view, 

 be divided into several categories or groups. That is the double dis- 

 covery of fundamental importance for which Landsteiner was awarded 

 the Nobel prize — a discovery whose origin is to be found in the great 

 volume of research devoted for a quarter of a century to the serological 

 properties of the blood. 



How should the facts brought to fight by Landsteiner bo inter- 

 preted? The simplest explanation, and the one most usuafiy given at 

 the present moment, is that iso-agglutination results from the recip- 

 rocal action of two kinds of substances whose chemical nature, how- 

 ever, remains completely unknown; the one called agglutinogen is 

 contained in the red corpuscles, the other, or agglutinin, is in the serum. 

 Analysis has shown that there are at least two different agglutinogens, 

 conventionally called A and B * and capable of being present in the 



' la this deliberately simplified descriptiou, we are not taking into account either agglutinogens or acces- 

 sory agglutinins. 



