3 o8 HEREDITY AND DISEASE 



in any case, the fact is that we consistently try to conserve lives 

 which natural selection would eliminate. This may be for social 

 reasons necessary, but it cannot be regarded with satisfaction 

 unless it is associated with positive selection of the fitter types. 



It has often been said that modern hygiene, in tending to 

 eliminate our eliminators the microbes is destroying a most 

 valuable selective agency which has helped to make our race 

 what it is. 



It is difficult to find justification for the enthusiastic confidence 

 which some seem to have in the value of microbes as eliminators. 

 Which microbe ? Surely not that of plague, which strikes in- 

 differently, and is no more discriminatively selective than an 

 earthquake. Surely not that of typhus, which used to kill weak 

 and strong alike. Surely not that of typhoid, which may strike 

 anyone, and does not confer more than a passing immunity. 

 And so on through a long list. 



It would perhaps be a subtler and more convincing line of 

 argument to say that, throughout the ages, man has been select- 

 ing the microbes, lessening their virulence, in a sense taming 

 them sometimes to death as his phagocytes were strengthened 

 by more suitable food, or as his " Opsonic Index " improved, 

 again perhaps in relation to food. As the body increases in its 

 power of holding out and this is demonstrably modifiable it 

 can prolong the contest with intruding microbes with more and 

 more hope of ultimate victory. 



In any case, whether microbes have been important and 

 valuable selective agents or not, it is a sad confession on the 

 part of the " paragon of animals " if he cannot discover other 

 selective agencies more discriminating, let us hope to take 

 the place of disease germs. 



At present, we can only indicate that the future of our race 

 depends on Eugenics (in some form or other), combined with 

 the simultaneous evolution of Eutechnics and E ' Utopias. " Brave 

 words," of course ; but surely not " Utopian " ! 



