350 PHYSIOLOGICAL CHEMISTRY 



remembered that there is in many species a distinct immunity to the 

 action of the poison which the specific micro-organism produces. This 

 immunity depends either upon a destruction of the poison as by oxida- 

 tion, upon a combination between the poison and some constituents 

 of the active protoplasmic cells of the body, thereby rendering the 

 poison inactive, or, lastly, upon some action of the specific proto- 

 plasmic cells of the body usually affected by the poison, by which the 

 latter is unable to combine with the cells upon which it ordinarily 

 acts. All these suggestions, however, imply chemical reactions of 

 some kind, and obviously should be understood for a betterment of 

 our knowledge upon this important matter. 



Again, the specific immunity which shows itself after exposure to a 

 given disease, so that a second infection becomes practically impossi- 

 ble, can be explained satisfactorily only on chemical grounds, viz., by 

 the presence in the blood and lymph of certain protective or immuniz- 

 ing substances which presumably originate through chemical changes 

 in the blood-serum, under the influence of the bacteria causing the 

 disease. These are chemical substances, formed through chemical 

 decompositions or alterations of normal constituents of the blood, 

 and obviously we need to know more of their exact nature. 



Following Ehrlich's views, specific antitoxins, bactericidal sera, etc., 

 result from the overproduction of molecules in cells which are sensi- 

 tive to the action of toxins and other bacterial products. Antitoxins 

 so formed unite with toxins, and the so-called complementary bodies 

 and the bactericidal anti-bodies combine with the bacterial cells, thus 

 affording protection. These processes of alteration and combination, 

 however, are presumably all chemical, involving either alteration of 

 chemical structure, or direct combination of bodies chemically the 

 opposite of each other. Further, the so-called haptophor groups of the 

 toxin molecule are probably represented in fact by chemical groups 

 or radicles, which owe their power of combination with corresponding 

 groups of other cells to chemical affinity. Again, the complementary 

 body, normally present in all healthy blood-sera and which is needed 

 along with the specific anti-body for the destruction of bacterial cells, 

 must owe its activity to the power of chemical combination. Hence, 

 we have presented to us at every turn the question of the chemical 

 nature of these various substances, toxin and antitoxin, complement, 

 receptor, haptophor, etc., which are of such vital importance in the 

 production and maintenance of immunity and protection. Surely 

 this is one of the most important problems of the present day in the 

 domain of physiological chemistry, and calls for both patience and 

 skill of the highest order in its solution. 



