xui.] CRITICISMS ON « THE ORIGIN OF SPECIES:' 307 



parent stock In that case it is cither 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 per- 

 fectly 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 cir- 

 cumstances 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 Awiphipoda and Isopoda 

 over the higher Crustacea; Cetaceans and Seals over 

 the Primates, the civilization of the Esquimaux over 

 that of the European. 



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

 proceeded from the earlier, the whole developmental series, from the 



