GENETICS — MORGAN 359 



example, certain stigmata appear whose diagnosis is uncertain, an 

 examination of the family pedigree of the individual may help 

 materially in judging as to the probability of the diagnosis. 



I need scarcely point out those legal questions concerning the pa- 

 ternity of an illegitimate child. In such cases a knowledge of the 

 inheritance of blood groups, about which we now have very exact 

 genetic information, may often furnish the needed information. 



Geneticists can now produce, by suitable breeding, strains of popu- 

 lations of animals and plants that are free from certain hereditary 

 defects; and they can also produce, by breeding, plant populations 

 that are resistant or immune to certain diseases. In man it is not 

 desirable, in practice, to attempt to do this, except insofar as here 

 and there a hereditary defective may be discouraged from breeding. 

 The same end is accomplished by the discovery and removal of the 

 external causes of the disease (as in the case of yellow fever and 

 malaria) rather than by attempting to breed an immune race. Also, 

 in another way the same purpose is attained in producing immunity 

 by inoculation and by various serum treatments. The claims of a 

 few enthusiasts that the human race can be entirely purified or 

 renovated, at this later date, by proper breeding, have, I think, been 

 greatly exaggerated. Rather must we look to medical research to 

 discover remedial measures to insure better health and more happi- 

 ness for mankind. 



While it is true, as I have said, some little amelioration can be 

 brought about by discouraging or preventing from propagating well- 

 recognized hereditary defects (as has been done for a long time by 

 confinement of the insane), nevertheless it is, I think, through public 

 hygiene and protective measures of various kinds that we can more 

 successfully cope with some of the evils that human flesh is heir to. 

 Medical science will here take the lead — but I hope that genetics can 

 at times offer a helping hand. 



