168 GBOEGB JOHN EOMANBS I881- 



To Professor Meldola. 



Geanies : September 16, 1886. 



Dear Professor Meldola, — Physiological selection 

 seems to have brought a regular nest of hornets about 

 my head. If I had known there was to have been 

 so much talk about it at the British Association I 

 should have gone up to defend the new-born. If you 

 were there, can you let me know the main objections 

 that were urged? It seems to me there is a good 

 deal of misunderstanding abroad, due, no doubt, to 

 the insufficiency with which my theory has been 

 stated. In ' studying ' the paper, therefore, please 

 keep steadily in view that the backbone of the whole 

 consists in regarding mutual sterility as the cause (or 

 at least, the chief condition) instead of the result of 

 specific differentiation. This is just the opposite view 

 to that now held by all evolutionists, and, I believe, 

 by Darwin himself. (See ' Origin,' pp. 245-246 ; 

 ' Variation,' ii. pp. 171-176.) Now, if this view be 

 sound, my theory is obviously not restricted to any 

 one class of causes that may induce mutual sterihty. 

 Such cases may be either extrinsic or intrinsic as 

 regards the reproductive system ; they may be either 

 direct in their action on that system or indirect {e.g. 

 natural selection, or use and disuse, &c., producing 

 morphological changes elsewhere, which in turn react 

 on that system) ; therefore these causes may act 

 either on a few or on many individuals. Yet Wallace 

 does not seem to see this, but argues in the ' Port- 

 nightly ' that they can only act on an individual here 

 and there. 



