The first observations of agglutination of red blood cells caused by the serum of animals of other species dates back many years. The agglutination of red blood cells of some individuals, others by sera from the same species, is a recent development. Shattock observed this phenomenon for the first time with human blood.

(Continued). Current status of research relating to the number of  soagglutinins and isoaglutinógenos present in human blood.

Humans can be grouped into four groups according to the characteristics of the mutual reactions: binding and hemolytic sera were compared to erythrocytes.