To the Editor:
—I have received a large number of inquiries as to the technic in obtaining placental serum, mentioned in my paper, "Treatment of the Toxemias of Pregnancy" (The Journal, July 11, 1914, p. 158). The method is as follows: After the delivery of the child the cord is cut and the blood is allowed to flow freely from the placental end. A sterile flask collects the blood, which is then placed in a refrigerator until there is complete separation of the serum from the other elements of the blood. If the serum is perfectly clear and yellowish in color it may be used without further preparation; but if it is not, it may be centrifuged under aseptic precautions and then made perfectly clear.