NATURAL SELECTION 35 



since those specially liable to the disease tend to die 

 young and leave fewer offspring, natural selection is 

 increasing the immunity of our race to this scourge. 

 By cutting off those strains of blood particularly prone 

 to its attacks, nature is purifying the race from 

 susceptibility. 



It follows that, in considering the advisability of 

 extending the "crusade against consumption," in 

 building endless sanatoria for the patients, and expend- 

 ing vast sums of public money on curative measures 

 generally, we must carefully scan the proposed course 

 of action to discover whether we are or are not sacri- 

 ficing the welfare of numberless generations of the 

 future to secure the prolongation of the lives of some 

 of the sufferers in the present, and indulging our own 

 feelings of compassion at the expense of the future 

 well-being of our descendants. 



It seems that, broadly speaking, tuberculous patients 

 may be divided into two groups, one of which consists 

 of those who easily throw off the disease in favourable 

 circumstances, and one where the susceptibility is so 

 great that treatment can only be ameliorative. Dr A. F. 

 Tredgold says : 



" It is calculated that in the United Kingdom no 

 less than 90,000 people die annually from some form 

 of tuberculosis. This number is enormous, and yet 

 clinical experience and post-mortem examinations give 

 reason for thinking that probably another 90,000 

 become infected with the disease but make a complete 

 recovery. What is the explanation ? No doubt our 

 methods of treatment have enormously improved, but 

 the result, kill or cure, really depends to a very great 



