Ill CRITICISMS OX " THE ORIGIN OF SPECIES " 91 



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 natur-al selection under these circum- 

 stances would tend, on the whole, to the weeding 

 out of the higher organisms and the cherishing of 

 the lower forms of life. Cryj)togamic 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 

 civilisation 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 simplest to the highest, could not now exist ; in such a case- 

 the simpler organisms must have disappeared." 



To this Professor Kolliker replies, with perfect 

 justice, that the conclusion drawn by Pelzeln does 

 not really follow from Darwin's premises, and that, 

 if we take the facts of Palaeontology as they 

 stand, they rather support than oppose Darwin's 

 theory. 



" 6. Great weight must be attached to the objection brought 

 forward by Huxley, otherwise a warm supporter of Darwin's 

 hypothesis, that we know of no varieties which are sterile with 

 one another, as is the rule among sharply distinguished animal 

 forms. 



" If Darwin is right, it must be demonstrated that forms may 

 be produced by selection, which, like the present sharply dis- 

 tinguished animal forms, are infertile, when coupled with one 

 another, and this has not been done." 



