6 ADAPTATION AND DISEASE 



The Nature of Variation 



The supreme biological problem of our times has been that 

 of the ways and means of evolution. The fact of evolution 

 all thinking minds accept. But as to how evolution has been, 

 and is being, brought about is a very different matter. There 

 is still as much debate as there was in the year following the 

 publication of the Origin of Species. Upon consideration 

 it will be seen that the fight truly centres upon the cause or 

 causes of variation — whether the tendency to vary is something 

 inherent in living matter, numerous variations being produced 

 through this inherent tendency, of which those that are best 

 fitted for their environment alone survive and are perpetuated : 

 or whether variation is primarily and essentially brought about 

 by the influence of forces acting from without upon a relatively 

 labile living matter ; whether, that is, variation 1 is primarily 

 inherent, proceeding from within, or primarily acquired, proceeding 

 from without. 



This, I would emphasize, is the basal problem of evolution, 

 but oddly enough it has been largely neglected, the fight through 

 all the years waging around what, after all, is a secondary problem, 

 that, namely, as to whether properties acquired by the parent 

 are capable of being transmitted to and reproduced in the off- 

 spring. Long years prior to Darwin, you will remember, Lamarck 

 propounded that they were, as did Erasmus Darwin and Lord 

 Monboddo ; Darwin wanted to believe that this was possible, 

 but could obtain no clear evidence, and brought in finally a 

 verdict of " non proven." Herbert Spencer made this trans- 

 mission one of his " principles of biology," but Weismann 

 violently opposed the doctrine, carrying with him the bulk of 

 latter-day biologists, until to-day Bateson, replete with his 

 studies upon Mendelian properties, reaches the antipodal sugges- 

 tion that when a new property manifests itself in any individual 

 of any species it is not new, not due to addition, but to subtrac- 

 tion and loss of properties already possessed : there is nothing 

 new under the sun, and, in his opinion, evolution — like the squid — 

 progresses backwards ; what appears to be a new property is, on 



1 By an oversight this was delivered as " variability " at the Royal College 

 of Physicians and so printed in the pages of the British Medical Journal. Pace 

 Sir Ray Lankester (for whose criticism consult the correspondence at the end 

 of this volume), my meaning was as obvious as was the oversight. 



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