blood types Nowadays in Japan, most people know their own blood types. But until the beginning of the 20th century, blood types didn't exist. At that time, a blood transfusion was left up to chance. Some people were saved by a blood transfusion and other people were killed by a blood transfusion. How did it happened? To solve this problem, Karl Landsteiner, who was an Austrian biologist, experimented about this problem.

He focused on blood aggregation. First, he separated the blood into blood cells and plasma. He mixed person’s blood cells with another’s plasma. He observed the reaction to various combinations. There were combinations aggregating or not aggregating.

He discovered it had a regularity. Based on these results, he distinguished the main blood types.

After that, it was found from Karl Landsteiner’s experiment that the main reason of blood transfusion accidents was blood type incompatibility. Blood transfusion accidents decreased sharply. This experiment contributed to the development of medicine.