124 J ALONE LTAVILER [AUGUST 
to be of more importance than the mere conditions of climate, ete., 
and inasmuch as climatic selection will largely cease acting as soon 
as organisms, capable of surviving at all under these altered con- 
ditions, are produced, it follows that inter-organismal action, which 
is continuous, must be of more importance in species formation and 
differentiation of structure. But as organisms which cannot survive 
under these altered conditions will be eliminated, it follows that the 
more obvious structural changes will be largely produced by this 
temporary climatic selection, and this form of selection will be re- 
markably rapid in its action relatively to the inter-organismal 
selection. Hence the obvious structural changes induced by climatic 
selection will have less chance of leaving a geological record behind 
them than the less obvious variations induced by inter-organismal 
selection. For this reason certain imperfections in the record are 
likely, and should be expected, to arise. 
6. Lhat the period of time is too short for such great alterations 
of structure to have taken place—aAs the rapidity or slowness of 
structural alterations will depend on the local surrounding conditions, 
it follows that, until some fairly complete record of these local condi- 
tions is obtainable, no objection as to time limit can be logically 
raised. 
7. The co-ordination of parts necessary for the development of 
favourable adaptations.—Spencer has pointed out that co-ordination 
of many parts to form one adaptation is based on a different principle 
to the cumulative results of many different variations each of which 
is of selective value, and urged that natural selection is powerless to 
explain this co-existent adaptation. 
Wallace, in referring to this subject, says :—“ The fact, that in all 
domestic animals, variations do occur, rendering them swifter or 
stronger, larger or smaller, stouter or slenderer, and that such varia- 
tions can be selected and accumulated for man’s purpose, is sufficient 
to render it certain that similar or even greater changes may be 
effected by natural selection, which as Darwin well remarks ‘acts on 
every internal organ, on every shade of constitutional difference, on 
the whole machinery of life” The difficulty as to co-adaptation of 
parts by variation and natural selection appears to me, therefore, to 
be a wholly imaginary difficulty which has no place whatever in the 
operations of nature.”' This criticism does not appear to me to do 
justice to Spencer’s objection; he would no doubt agree with Wallace 
that these accessory variations can be developed by selection, but he 
would go one step farther back and ask why it is that the accessory 
variations happen to be there to be selected from at all. He would 
agree to the fact that selection must act on the whole machinery of 
life, but he would still urge that he is unable to see how it is that all 
these numerous accessory variations which are necessary to the working 
1 “*Tyarwinism,” p. 418, 
