30 THE PROTEOMORPHIC THEORY AND THE NEW MEDICINE 



ceptible of application in dealing with a wide range of maladies 

 associated with disturbances of protein metabolism. 



All this will be taken up in detail as we proceed. Our first 

 concern, however, is with the previously established facts as to 

 the systemic response to the invasions of proteins chiefly of the 

 bacterial order. 



FACTS AND THEORIES OF IMMUNITY 



For generations physicians have been aware that an attack 

 of a contagious disease tends to give the subject immunity against 

 further attacks of that disease. The discovery of Jenner gave 

 an inkling of the possibilities of preventing disease by inocula- 

 tion, but this purely empirical procedure did not lead directly 

 to any extension of the method. It was only after the bac- 

 teriologist had discovered the tangible cause of disease that a 

 way was found to produce artificial immunization. 



In 1887 Pasteur startled the world by demonstrating that a 

 virulent bacillus could be attentuated as to its virulence by cul- 

 tivation in an artificial medium, and that an animal inoculated 

 with the virus thus produced was given immunity from the dis- 

 ease, even though subsequently inoculated with virulent germs. 

 In 1890 Behring discovered that the blood of an animal thus 

 immunized has power to transmit the immunizing principle, what- 

 ever it might be, to another animal if the blood serum of the 

 immune animal is injected hypodermatically or intravenously. 

 The diphtheria antitoxin thus developed by Behring, and a tet- 

 anus antitoxin discovered by Behring and Kitasato, were soon 

 added to the armamentarium of the physician. 



At about the same time, Ehrlich conducted his classical series 

 of experiments with vegetable poisons, notably ricin and abrin 

 (the toxic principles, respectively, of the castor-oil bean and the 

 seed of jequirity). He found that an animal inoculated with 

 either of these proteid substances developed an immunizing prin- 

 ciple which, when mixed with the poison itself in vitro neutralized 

 the poison. It was necessary to make the admixture in certain 

 proportions, thus showing the chemical nature of the reaction. 

 Ehrlich thought of the phenomenon in chemical terms ; yet, for 

 the purpose of bringing the matter vividly to the attention of the 

 profession, he devised a mechanical scheme in explanation of the 

 phenomenon of immunity which soon found almost universal 

 acceptance, and which is often incorrectly thought of as suggest- 

 ing something quite different from chemical combinations. 



Ehrlich's tangible diagrams showing his "receptors" of the first, 

 second, and third order ; his haptophores and toxophores ; his 

 zymorphous and complementophile groups of the complex all 



