The old axiom, "blood will tell," has been given a new lease on life by the work of biochemists and hereditists in the last thirty years. At the beginning of the twentieth century a scientist, Karl Landsteiner, working on the means to make blood transfusions safe, discovered that the New Testament saying, the Almighty "hath made of one blood all nations of men," is not true. He found that human blood is divided into four groups, characterized by the possession or non-possession of certain substances in the serum and the corpuscles of the blood. If one puts a little blood into a glass container, and then adds a little blood taken from another person, one of two things may result. Either the two bloods will mix freely, or the red cells of the mixture may lump together and fall to the bottom of the container, leaving a clear liquid. This latter is the phenomenon of agglutination, the basis of the blood-group test. From this property of the human blood, that of clumping or not clumping when mixed with blood of another person, scientists posited the four blood groups, O, A, B, and AB, into which all human beings seem to fall. To find out to which group a given person belongs, a sample of his blood is mixed with samples of blood from those whose blood group is known. By observing whether the unknown blood mixes or clumps, the group to which the unknown blood belongs can easily be determined. Hospitals, the country over, go through this process with every applicant for blood transfusions, so that no blood will be introduced into a sick man's veins which will agglutinate his blood and probably cause his death. While it is true that "there is no caste in blood," it is nevertheless equally true that human blood can be classified, and this classification holds true throughout the world.

Soon after the blood-group test had been described, it was suggested that it be applied practically in the courts for distinguishing the bloods of different individuals. Has the blood group any real place in the court room? This is our fundamental query.