Alfred Russel .Wallace 



by Romanes had no real weight because the possibility of 

 so-called " co- adaptations " being developed successively in 

 the order of evolution had not been reckoned with. There 

 was no real divergence between Wallace and Prof. Meldolu 

 on this matter when they subsequently discussed it. The 

 correspondence is in Nature^ xliii. 557, and subsequently. 

 See also " Darwin and After Darwin," by Romanes, 1895, 

 ii. 68. 



To Prof. Meldola 



Parkstone, Dorset. April 25, 1891. 



My dear Meldola, — You have now put your foot in it! 

 Romanes agrees with you! Henceforth he will claim you 

 as a disciple, converted by his arguments ! 



There was one admission in your letter I was very sorry 

 to see, because it cannot be strictly true, and is besides 

 open to much misrepresentation. I mean the admission 

 that Romanes pounces upon in his second paragraph. Of 

 course, the number of individuals in a species being finite, 

 the chance of four coincident variations occurring in any 

 one individual — each such variation being separately very 

 common — cannot be anything like '' infinity to one." Why, 

 then, do you concede it most fully ? — the result being that 

 Romanes takes you to concede . that it is infinity to one 

 against the coincident variations occurring in '' any in- 

 dividuals/^ Surely, with the facts of coincident inde- 

 pendent variation we now possess, the occurrence of three, 

 four, or five, coincident variations cannot be otherwise 

 than frequent. As a fact, more than half the whole popu- 

 lation of most species seems to vary to a perceptible and 

 measurable, and therefore sufficient, amount in scores of 

 ways. Take a species with a million pairs of individuals 

 — half of these vary sufficiently, either + or — , in the four 

 acquired characters A, B, C, D : what will be the propor- 

 tion of individuals that vary + in these four characters 



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