ENZYME ACTION AND ADAPTATION 89 



continues, so gradually will there be developed a tendency for 

 the proportion of the radicles constituting the biophoric mole- 

 cules to vary, those deficient in number being replaced by those 

 that are abundant. 



Or again, the simpler complexes due to the breaking down 

 of the foreign protein may not be identical in constitution with 

 those which prior to the exhibition of the foreign protein had 

 been attracted to and had constituted certain particular side- 

 chains of the biophoric molecules. In this way again the con- 

 stitution of the biophores may become altered. This we may 

 visualize as follows (Fig. 9) : 





N _ _ 



I 

 c 



=c 



FIG. 10. Pyrimidine ring. 

 Fia. 9. 



I would recall how a slight difference in the relative attachments 

 of the side-chains, say, of the Pyrimidine ring (Fig. 10) alters the 

 chemical properties of the compound : 1 in like manner what 

 may appear to be but a slight modification in the constitution of 

 a biophoric side-chain may be expected to lead to material 

 differences in the reactions of the whole molecules, that is, in 

 the case of germinal biophores, of the individual. 



1 I came to these views honestly through a respectable collateral heredity. 

 My mother's brother, the late Dr. D. J. Leech, of Manchester, as the subject of 

 his Croonian Lectures at the Royal College of Physicians in 1893 discussed the 

 pharmacological action of the nitrates, comparing and contrasting the action 



of the nitrates, - - N= 0, the nitrates, - - N^Q, the nitro compounds, 

 - N^~, the nitrosamines, = N=N - 0, and the oximes, =N - - H. He was 



one of the first English pharmacologists to dwell upon the modification in the 

 action of drugs brought about by slight differences in the order of attachment 

 or composition of radicles. (See the British Medical Journal, 1903, and his 

 collected papers upon " The Pharmacological Action and Therapeutic Uses 

 of the Nitrates," edited by Dr. R. B. Wild, Manchester, 1902.) 



