Karl Landsteiner (June 14, 1868 - June 26, 1943), was an Austrian biologist and physician. He is noted for his development in 1901 of the modern system of classification of blood groups from his identification of the presence of agglutinins in the blood, and in 1930 he received the Nobel Prize in Physiology or Medicine. With Alexander S. Wiener, he identified the Rh factor in 1937. He was awarded an Lasker Award in 1946 posthumously.
Landsteiner was aware of Stillmark's work with lectins, and wrote in a paper 1914 entitled 'Pflanzliche Hammagglutinine." that he had observed that these extracts did not always agglutinate the blood of different species equally.
In 1908 he had reported that small amounts of lentil lectin would agglutinate rabbit erythrocytes, even high concentrations of the lectin had no effect on pigeon red cells.
This paper reached the stage of page proof, but owing to the war of 1914 was never published until the first edition of his book (1933) "Die Spezifizitat der Scrologischen Reaktionen."