Page:The Zoologist, 4th series, vol 3 (1899).djvu/341

Rh fence. Grazing cattle will not touch plants that would be deadly or hurtful to them; but if taken to a distant land, to another continent where unknown herbs grow they are unable to distinguish, they sicken or die of the poison they have eaten.

But perhaps it is only by recognizing the full force of the objections that we can hope to fairly realize the strength of the theory thus called in question. If these mimicking or protective disguises have not been incidental to a phase of evolution, they must have been created as they are, and even the advocates of this view—if any competent are left—would surely not enunciate the idea of a purposeless creation, or the fanciful freaks of a Demiurgos, for such must be the case if no purpose is served by these extraordinary imitations. On the other hand, what can the evolutionist reply when he is confronted with the only other postulate of astonished ignorance expressed in the terms of "a freak of nature"?

The solution of the difficulty may—we repeat—probably be found in ceasing altogether to explain some biological features of the past by causes operating in the present, and perhaps only in the present epoch. In fact, many animals affording undoubted instances of protective resemblance and mimicry now show in the observed dangers of their lives, so little raison d'être for these wonderfully evolved assimilations in colour and structure, that it seems more philosophical to conceive them as survivals of a past when there was a greater danger and a larger need.