ADAPTATION 205 



The discoveries of the last twenty years have proved 

 beyond all doubt, and future discoveries will probably prove 

 even more conclusively, that the so-called immunity against 

 diseases is but one case out of numerous biological pheno- 

 mena in which there is an adaptive correspondence between 

 abnormal chemical stimuli and active chemical reactions on 

 the part of the organism and in its interior, exceeding by 

 far everything that was formerly supposed to be possible 

 in organic regulation. 



The adaptive faculty of the organism against inorganic 

 poisonous substances * is but small comparatively, and is 

 almost always due not to a real process of active regulation 

 but to the action of substances pre-existing in the organism 

 that is, to a sort of adaptiveness but not adaptation. 

 Metallic poisons, for instance, may be transformed into 

 harmless compounds by being combined with albumen or 

 sulphuric acid and thus becoming insoluble, or free acids 

 may be neutralised, and so on ; but all these processes 

 go on to a certain extent only, and, as was mentioned 

 already, are almost always the result of reactions with 

 pre-existing materials. Only in a few cases is there any 

 sort of true adaptation to metallic substances, such as 

 sublimate and, in a very small degree, arsenic, comparable 

 in some respects with the adaptation to abnormally high 

 temperatures. The organism which has been accustomed 

 to receive at first very small amounts, say, of sublimate, and 

 then receives greater and greater amounts of this substance 

 by degrees, will at the end of this treatment be able to 

 stand a quantity of the poison that would have been 



1 A good review is given by E. Fromm, Die chemischcn Schutzmittel des 

 Tierkorpers bei Vergiftungen, Strassburg, 1903. 



