When a person loses a great deal of blood for one reason or another, his life can often be saved by a blood transfusion. The blood of another person is put into the circulatory system and replaces his lost blood.
The first recorded blood transfusion was performed in 1677, when the blood of a lamb was injected into the veins of a dying boy. That boy was lucky and recovered. We now know that the blood of lower animals is different from human blood and cannot be used for transfusions with safety.
In 1940, it was found that there was still another way of dividing blood groups, and this was according to the Rh factor. This discovery was made in the course of experiments on rhesus monkeys, and that’s why it came to have the name “Rh”.
It was found that when certain combinations of blood were made, the red blood cells broke apart. The cause was traced to certain differences in the Rh factor.
The blood of human beings in this case is divided into Rh positive and Rh negative. When blood from an Rh-positive person is transfused to a person who is Rh-negative, the latter will develop a blood disease when he receives Rh-positive blood again.
In rare cases, an Rh-positive father and Rh-negative mother will produce an infant with a blood disease if certain other conditions exist.