The development of biologic products used for prophylactic and therapeutic purposes has been so extensive that confusion exists as to the value of some of the agents of this group, and a brief discussion of the subject at this time is warranted.
The brilliant results which followed the use of the first agents of this group, notably vaccine virus, antidiphtheric serum and antitetanic serum, have not been duplicated by the majority of those that have come into use in recent years.
In this country products of this class may not be imported, exported, or sold in interstate commerce without a license issued to the manufacturer by the secretary of the treasury, which license is based on a careful investigation of methods of the manufacture of the products and conditions surrounding it.
The license means in effect that products are produced under conditions which should insure freedom from dangerous contamination and,