THE WORLD OF LIFE. 



641 



weight. The author then proposes to " enumerate briefly the exact 

 causes [?] which must [?] have been at work in bringing about the 

 changes [?] in the rabbits of Porto Santo." "Up to this time, 

 perhaps nol more than a dozen or twenty years from their first intro-., 

 duction, they would have varied in size and colour, as do common 

 domesticated races, from which Darwin thinks they were 

 undoubtedly derived." Then follow seven " causes " which " would "■ 

 operate. He concludes: " We thus see that all the changes that have^ 

 occurred have no relation whatever to mere * isolation,' which many 

 writers still persist in claiming as a vera causa of specific change." 



Of course, " mere isolation " is not the " cause," but the " direct, 

 action of the changed conditions of life," of a new environment, as 

 Darwin says,'^ produces the "results" which he calls "definite," 

 when all the individuals vary alike, by means of the responsive power 

 of life, in adaptation to those conditions, " without any selection." 



The words we have itahcized — viz. " they would have varied " — lie 

 at the root of the matter. What we want to know is. Why did " grey " 

 become "reddish-brown," and why did the size decrease? 



If they are all of the latter colour now, the " numerous enemies," 

 which at first selected the " larger, more bulky, and slower-moving 

 individuals," still keep them down, though smaller and reddish-brown, 

 and, one supposes, maintain the average number. But surely " hawks, 

 buzzards, falcons, and owls" would not really be so discriminating. 

 Would they not pounce upon the first they could see, whatever the 

 pace, colour, and size? The fact is, Darwin's title was misleading. 

 New species do not arise " by means of natural selection," but (and- 

 he confesses, in his letter to Wagner, that it was his greatest mistake 

 in overlooking it) by the young animal or plant responding to the 

 changed conditions of life. These excite the variability, in the 

 organisms, and adaptive changes in its colour and structure follow 

 accordingly.! Hence Darwin eliminates natural selection altogether. 

 In its place is what he calls " fortuitous destruction." 



Sir E. Ray Lankester gives an excellent illustration of this in the 

 case of the oyster. He tells us that a single oyster umy discharge 

 upwards of a million eggs. Fishes, &c., devour enormous quantitieji. 

 Others fall on unsuitable places. So that — as the average oyster 

 population remains the same — perhaps one only falls on a suitable 

 spot. What is true of one is true of all oysters. There is obviously 

 no selection, only fortuitous destruction. Nevertheless, there are 

 varieties of oyster, found in different situations — smaller, longer, and 

 of different characters. 



Dr. Wallace would eliminate the "less adapted" by destruction; 

 but Darwin maintains that all the ojf spring can vary alike, I and there- 



* Animals and Plants under Domestication, ii. p. 271 ff, 

 t We shall see that Dr. Wallace recognizes this below. 



t Origin of Species, &c. Sixth edition, p. 80 : "All the individuals varying 

 in the right direction . . . will tend to be preserved." In First edition : 

 "Natural selection will always tend to preserve all the individuals varying 

 in the right direction." 



VOL. XXXVI. 



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