nr CRITICISMS ON “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 natural 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. Cryptogamic vegetation 
would have the advantage over Phanerogamic ; 
Hydrozoa over Corals; Crustacea over Insecta, and 
Amphipoda and Jsopoda 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 Paleontology. 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. 
*<Tf 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.” 
