Page:Popular Science Monthly Volume 78.djvu/220

220 nitrites, the sera and vaccines, the animal extracts. In this list it will be noted that of the few actual drugs left from the vast accumulation of centuries, nearly every one has a specific intention.

The idea of specificity in the treatment of disease had its origin in Jenner's immortal discovery of preventive inoculation, but first began to attain its full growth with the development of the bacterial theory of infection. Pasteur's preventive inoculations in anthrax and hydrophobia made a good start in the right direction, but the temporary failure of Koch's tuberculin showed that the path was a perilous and thorny one even for a man of genius. Behring's discovery of antitoxins and the success of his diphtheria antitoxin opened out new aspects of the subject, but pure serotherapy with stock antitoxins has been so far effective only in diphtheria, tetanus and serpent poisoning. The work of Sir Almroth Wright and his followers made it clear that antitoxic and antibacterial immunity are two entirely different things. In the latter case, the immunity or cure is not brought about by the dovetailing of the chemical bonds of toxins and antitoxins, but by stimulating the tissues to produce opsonic or sauce-like materials which make the pathogenic organisms more easily absorbable by the white blood corpuscles. This is the phagocytosis of Metchnikoff and is best attained by the injection of dead cultures or vaccines of the organisms producing the disease. Vaccinotherapy has been so far successful in such blood poisonings as puerperal septicæmia or furunculosis, in gonorrhœal rheumatism, and particularly in preventive inoculations against typhoid fever. In such a toxæmia as puerperal fever, the infection may be due to many different bacteria and here the treatment reaches such a high degree of specificity that it becomes, in effect, individual and autogenous, the vaccines being prepared from the blood of the lying-in woman to attain the Ehrlich ideal of "charmed bullets." In typhoid fever, the success in the case of some 14,000 United States soldiers recently vaccinated against the disease under the direction of Major F. P. Russell, has been such that Major Russell thinks the time has come when this preventive measure should be extended to the civil population also. The discovery that a large number of specific infections—notably malarial fever, sleeping sickness, relapsing fever, hook-worm infection and syphilis—are due to animal parasites, revealed still another class of diseases requiring specific treatment—a class which probably includes cancer, rheumatic fever, smallpox, yellow fever, pellagra, hydrophobia and most diseases of the skin. Ehrlich was late in entering this field of specific therapeutics, but he immediately began to dominate it, for it was he who put the treatment of protozoan infection upon a scientific basis. Having discovered that animal parasites can immunize themselves against the action of