PDF - Wallace Online

in PROTECTIVE RESEMBLANCES AMONG ANIMALS 77in other cases, with the addition of a few that are peculiar toit. The most obvious is, that we have gradations of mimicryand of protective resemblance a fact which is stronglysuggestive of a natural process having been at work. Anothervery serious objection is, that as mimicry has been shown tobe useful only to those species and groups which are rare andprobably dying out, and. would cease to have any effect shouldthe proportionate abundance of the two species be reversed,it follows that on the special-creation theory the one speciesmust have been created plentiful, the other rare ; and, notwithstandingthe many causes that continually tend to alterthe proportionsof species, these two species must have alwaysbeen specially maintained at their respective proportions, orthe very purpose for which they each received their peculiarcharacteristics would have completely failed. A third difficultyis, that although it is very easy to understand howvariation and the survivalmimicry may be brought about byof the fittest, it seems a very strange thing for a Creator toprotect an animal by making it imitate another, when thevery assumption of a Creator implies his power to create itso as to require no such circuitous protection. These appearto be fatal objections to the application of the special-creationtheory to this particular case.The other two supposed explanations, which may beshortly expressed as the theories of " similar conditions " andof " heredity," agree in making mimicry, where it exists, anadventitious circumstance not necessarily connected with thewell-being of the mimicking species. But several of the moststriking and most constant facts which have been adduceddirectly contradict both these hypotheses. The law thatmimicry is confined to a few groups only is one of these, for" similar conditions " must act more or less on all groups in alimited region, and "heredity" must influence all groupsrelated to each other in an equal degree. Again, the generalfact that those species which mimic others are rare, whilethose which are imitated are abundant, is in no way explainedby either of these theories, any more than is the frequentoccurrence of some papable mode of protection in the imitated"species. Reversion to an ancestral type " no way explainswhy the imitator and the imitated always inhabit the very