Medicine: Blood Test

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Governor Herbert Lehman of New York last week signed a law which requires every man, woman and child to supply samples of his blood whenever such blood tests are relevant to the prosecution or defense of a lawsuit. Such tests are sometimes the crux of legal actions to establish the paternity of a child. A few judges in New York, Pennsylvania, Connecticut and South Dakota have on their own responsibility accepted blood tests as true evidence. But New York is the first state to incorporate the new science of serology in a statute and to recognize that there are at least twelve different types of human blood and that the blood group to which an individual belongs depends exclusively upon the type of blood which flowed through the veins of his father and mother.

No one was happier over the signing of the law than Dr. Alexander Solomon Wiener, young Brooklyn pathologist who lobbied for its passage, who, with the promptings of his lawyer-father, has become the country's best-known court expert on blood groups, and who last week produced a timely compilation of what reliable scientists know about the whole subject.*

According to those authorities, the simplest divisions of human blood types are those discovered in 1900 by Dr. Karl Landsteiner of the Rockefeller Institute. Dr. Landsteiner first found that, when he mixed the red cells of one person with the blood serum of another, occasionally the red cells agglutinated. Cause of the occasional clumping, he found, was an antibody in the serum which was antipathetic to an agglutinogen in the red cells. Further research disclosed two agglutinogens, A and B. A person's red cells might contain A or B, or both (AB) or neither (O). Thus, according to their blood, there are four kinds of people in the world—A, B, AB, and 0. Every father and mother transmit definite blood factors to their child. Thus the offspring of parents with O and O blood can have only 0 blood and not A, B or AB blood. The child of 0 and A parents might have either 0 or A blood but not B or AB blood. If one parent has A blood and the other B, their child might have any of the four kinds—hence frustrating the test.

Recently serologists discovered two more telltale constituents of the blood, called M and N factors. Every person's blood contains M, N or MN. No one lacks them. By taking M and N into consideration in addition to A and B, blood experts can solve two out of every three cases of mixed babies, one out of every three cases of disputed paternity.