6 QUATERCENTENARY STUDIES IN PATHOLOGY 



III. Death-rates and Deterioration of Stock. 



In passing, perhaps it is worth noting that to reduce the death-rate 

 of a disease does not mean to confer immortality on the patient. If he 

 does not die of phthisis, he will die of something else ; but it is 

 probable that if he does not die of phthisis, he will live at least a little 

 longer before he dies of anything else. So elementary a fact should 

 not be worth stating ; but it is worth stating, for I seem to detect in the 

 occasional disappointment with the slow fall of death-rates an 

 unexpressed, perhaps unconscious belief, that they ought to go down to 

 nothing per cent., which is immortality. This, of course, is not com- 

 patible with the conditions of life known in this world ; we must be 

 satisfied with deferred death. The important fact is that when we save 

 a case from death by consumption, we are effecting a real, not an 

 apparent, saving. For there is no evidence that the extirpation of 

 consumption means the establishing of any other fatal disease. It has 

 been contended that by saving a larger number of tubercular people — 

 of course the tubercular diathesis is itself an hypothesis only — we 

 ultimately contribute to the deterioration of the race by a geometrical 

 increase of feeble constitutions. The argument applies to every infec- 

 tion ; but by long tradition it has, in the popular mind, a special 

 application to phthisis. Personally, I have not been able to discover a 

 sound reason for the argument. If we make it cut the other way, we 

 ought, logically, to assume that every cause of death whatsoever permits 

 the survival of a greater number of deteriorated stocks. But it is 

 possible to classify causes of death into selective and non-selective. 

 There is, however, no obvious or immediate test to enable us to 

 discriminate which disease is selective and which non-selective. It is 

 pure hypothesis to assume that phthisis is one of the selective causes, 

 and that every person that dies from it is better dead than living. 

 Neither for phthisis nor for any other infection have we any data of the 

 slightest value to enable us to give a conclusive solution of that 

 problem. In our efforts to limit the spread of tuberculosis, we may 

 assume, meanwhile, that every reduction in the death-rate is a social gain. 

 It is pitiful to learn that superstitions about Natural Selection, which is 

 not a god, but an abstraction, sometimes divert public funds to other 

 uses. It is more pitiful to learn that men with an elementary training 



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