XIIL] CRITICISMS ON &quot; THE ORIGIN OF SPECIES.&quot; 267 



tendency of organisms to give rise to useful varieties, and knows 

 nothing of needs of development, or necessity of perfection. What 

 he says is, in substance : All organisms vary. It is in the highest 

 degree improbable that any given variety should have exactly 

 the same relations to surrounding conditions as the parent stock. 

 In that case it is either better fitted (when the variation may be 

 called useful), or worse fitted, to cope with them. If better, it 

 will tend to supplant the parent stock ; if worse, it will tend to 

 be extinguished by the parent stock. 



If (as is hardly conceivable) the new variety is so perfectly 

 adapted to the conditions that no improvement upon it is 

 possible, it will persist, because, though it does not cease to 

 vary, the varieties will be inferior to itself. 



If, as is more probable, the new variety is by no means 

 perfectly adapted to its conditions, but only fairly well adapted 

 to them, it will persist, so long as none of the varieties which it 

 throws off are better adapted than itself. 



On the other hand, as soon as it varies in a useful way, i.e.. 

 when the variation is such as to adapt it more perfectly to its 

 conditions, the fresh variety will tend to supplant the former. 



So far from a gradual progress towards perfection forming any 

 necessary part of the Darwinian creed, it appears to us that it is 

 perfectly consistent with indefinite persistence in one state, or 

 with a gradual retrogression. Suppose, for example, a return of 

 the glacial epoch and a spread of polar climatal conditions over 

 the whole globe. The operation of natural selection under these 

 circumstances would tend, on the whole, to the weeding out of 

 the higher organisms and the cherishing of the lower forms of 

 life. Cryptogamic vegetation would have the advantage over 

 Phanerogamic ; Hydrozoa over Corals ; Crustacea over Insecta, 

 and Amphipoda and Isopoda over the higher Crustacea; 

 Cetaceans and Seals over the Primates ; the civilization of the 

 Esquimaux over that of the European. 



u 5. Pelzeln has also objected that if the later organisms have proceeded 

 from the earlier, the whole developmental series, from the simplest to the 

 highest, could not now exist ; in such a case the simpler organisms must 

 have disappeared.&quot; 



