PROBLEMS OF PHYSIOLOGICAL CHEMISTRY. 165 



certain bacteria possessed by some animals is due in large measure to an 

 inhibition of the growth of the micro-organism, it must also be remem- 

 bered that there is in many species a distinct immunity to the action 

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

 munity depends either upon a destruction of the poison as by oxidation, 

 upon a combination between the poison and some constituents of the 

 active protoplasmic cells of the body, thereby rendering the poison 

 inactive, or, lastly, to some action of the specific protoplasmic 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 sug- 

 gestions, 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 impossible, 

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

 presence in the blood and lymph of certain protective or immunizing 

 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 sensitive 

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

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

 the bactericidal antibodies combine with the bacterial cells, thus afford- 

 ing protection. These processes of alteration and combination, how- 

 ever, are presumably all chemical, involving either alteration of chem- 

 ical 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, nor- 

 mally present in all healthy blood sera and which is needed along with 

 the specific antibody 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. 



