HEREDITY BATESON. 385 



stored in the earth before man began it must soon become still more 

 fierce. In England some of our great-grandchildren will see the 

 end of the easily accessible coal, and, failing some miraculous dis- 

 covery of available energy, a wholesale reduction in population. 

 There are races who have shown themselves able at a word to throw 

 off all tradition and take into their service every power that science 

 has yet offered them. Can we expect that they, when they see how 

 to rid themselves of the ever-increasing weight of a defective popu- 

 lation, will hesitate? The time can not be far distant when both 

 individuals and communities will begin to think in terms of bio- 

 logical fact, and it behooves those who lead scientific thought care- 

 fully to consider whither action should lead. At present I ask you 

 merely to observe the facts. The powers of science to preserve the 

 defective are now enormous. Every year these powers increase. 

 This course of action must reach a limit. To the deliberate inter- 

 vention of civilization for the preservation of inferior strains there 

 must sooner or later come an end, and before long nations will realize 

 the responsibility they have assumed in multiplying these " cankers 

 of a calm world and a long peace." 



The definitely feeble-minded we may with propriety restrain, as 

 we are beginning to do even in England, and we may safely prevent 

 unions in which both parties are defective, for the evidence shows 

 that as a rule such marriages, though often prolific, commonly pro- 

 duce no normal children at all. The union of such social vermin 

 we should no more permit than we would allow parasites to breed 

 on our own bodies. Further than that in restraint of marriage we 

 ought not to go, at least not yet. Something, too, may be done by 

 a reform of medical ethics. Medical students are taught that it is 

 their duty to prolong life at whatever cost in suffering. This may 

 have been right when diagnosis was uncertain and interference 

 usually of small effect, but deliberately to interfere now for the 

 preservation of an infant so gravely diseased that it can never be 

 happy or come to any good is very like wanton cruelty. In private 

 few men defend such interference. Most who have seen these cases 

 lingering on agree that the system is deplorable, but ask where can 

 any line be drawn. The biologist would reply that in all ages such 

 decisions have been made by civilized communities with fair suc- 

 cess both in regard to crime and in the closely analogous case of 

 lunacy. The real reason why these things are done is because the 

 world collectively cherishes occult views of the nature of life, be- 

 cause the facts are realized by few, and because between the legal 

 mind — to which society has become accustomed to defer — and the 

 seeing eye, there is such physiological antithesis that hardly can 

 they be combined in the same body. So soon as scientific knowledge 

 18618°— SM 1915 25 



