CHAPTER VII 



CHEMICAL MEANS OF DEFENSE AGAINST 

 POISONS OF KNOWN COMPOSITION 



ALTHOUGH the examples of acquired immunity against poisons 

 of known chemical composition are few indeed, nevertheless the 

 body possesses means of defense against many such poisons, which 

 decrease to greater or less degree their harmful effects. True 

 immunity, associated with the production of neutralizing sub- 

 stances in the blood, has as yet been obtained only against sub- 

 stances of proteid nature or substances very closely resembling 

 the proteid s. Studies on bacterial immunity and allied topics 

 have as yet shown nothing to explain the acquirement of toler- 

 ance to morphine, alcohol, arsenic, and other similar poisons. 

 A few observers have claimed that the serum of animals 

 immunized to morphine will neutralize to some degree the toxic 

 effects of morphine, but these results have not been generally 

 substantiated. 1 Others have claimed that increased oxidative 

 powers are developed under the stimulation of the poison which 

 permits of its more rapid destruction, especially in the liver, but 

 the experimental support of this hypothesis is slight. Still 

 another idea is that, at least in the case of morphine, decomposi- 

 tion products are produced and accumulate in the body that 

 neutralize physiologically to some extent the morphine itself; this 

 hypothesis can scarcely be applied to arsenic and alcohol tolerance. 2 



It is possible, also, that the cell constituents with which the 

 poisons ordinarily combine are produced in increased amounts 

 under the stimulus of the poison, just as they are in the case 

 of immunization with toxins, with the difference that the com- 

 bining substances are not thrown off into the blood. For 

 example, it has been claimed that arsenic is ordinarily combined 

 and held in the liver by a nucleoproteid, and the suggestion 

 has been made that in arsenic habitues this nucleoproteid is 

 increased in amount. Again, saponin seems to act upon the 

 cholesterin of the red corpuscles, and Robert observed some 

 resistance to the action of saponin exhibited by the serum of 



1 See Morgenroth, Berl. klin. Woch., 1903 (40), 471. 



2 Concerning immunity against morphine see Faust, Arch. exp. Path. u. 

 Pharm., 1900 (44), 217; and Cloetta, ibid., 1903 (50), 453. 



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