NATURE 



265 



THURSDAY, JULY 20, 1882 



PERMANENCE AND EVOLUTION 



Permanence and Evolution j An Enquiry into the Sup- 

 posed Mutability of Animal Types. By S. E. B. 

 Bouverie Pusey. (London : Kegan Paul, Trench, and 

 Co., 1882.) 



THIS is a thoughtful little book, clearly and ably 

 written, with the view of showing, as its Preface 

 states, " that while Darwinism proper is improbable, 

 evolutionism in any form is as yet unproved ; while, on 

 the other hand, the more we investigate the facts of in- 

 heritance, the more we are compelled to regard differences 

 so slight, that they would usually be considered casual 

 variations, as within the limits of our existing knowledge 

 strictly permanent." Such being his theme, Mr. Pusey 

 introduces it with the following very appropriate and 

 judicious apology, which we quote in order to show the 

 spirit which throughout characterises his work. 



" It may seem almost presumptuous on the author's 

 part to attempt to reopen once more the whole question 

 of evolution, especially as in doing so it is necessary to 

 call in question the views of so many very eminent men 

 of science. At the same time, any one who calls attention 

 to any neglected facts, or who questions assumptions too 

 carelessly allowed to pass muster, helps to elucidate the 

 subject of which he treats, and so aids the cause of scien- 

 tific knowledge, whether the particular views he propounds 

 ate right or wrong." 



Having already observed that the work is one of 

 marked ability, we have only further to preface our 

 analysis of it by fully assenting to this justification. 

 Although, as we shall immediately proceed to show, we 

 do not think that Mr. Pusey has been successful in his 

 tilt againit the stone wall which has been reared by the 

 school of Darwin, we nevertheless respect his independent 

 disregard of mere authority, as we think that such disre- 

 gard always deserves to be respected in matters of science 

 where evidence is shown by the malcontent of clear and 

 forcible thought of his own upon the doctrines which he 

 undertakes to criticise. 



The principal part of " Permanence and Evolution " is 

 occupied with a criticism of the argument from classifica- 

 tion, and especially that part of the argument which has 

 reference to domestic animals. In the author's view Mr. 

 Darwin has failed to prove in the case of any domestic 

 animal that artificial selection has produced a new variety 

 or sub-species. Thus of the varieties of the dog he says, 

 "seeing how true they breed, I do not see why the prin- 

 cipal and best marked (the greyhound, the mastiff, the 

 terrier, the spaniel, &c.) should not have so existed (i.e. in 

 a state of nature), and the others have been formed by 

 crossing between them." Similarly of the pigeon he says 

 there is no sufficient evidence to show that all the fancy- 

 breeds were not once natural breeds which have since 

 become extinct as such, or that their occasional reversion 

 to the rock dove is not due to an ancient cross with it. 

 "As these races resemble the rock dove, and each other, in 

 everything except one or two conspicuous points, it need 

 not surprise us that they produce perfectly fertile off- 

 spring," &c. Thus also he treats of the cases of all the 

 other domestic animals alluded to by Darwin. 

 Vol.. xxti. — No. 664. 



Concerning this mode of criticism, it seems enough to 

 point out the cumulative improbability of all the domestic 

 races of animals having once been wild (notwithstanding 

 the apparent unfitness of some of them to a self-dependent 

 mode of life), added to the further cumulative improba- 

 bility of all these wild races having become extinct. We 

 do not say that the hypothesis is impossible, but clearly it 

 is so far improbable that even if there were no other evi- 

 dence of the mutability of animal types, it would be more 

 likely that the domestic races had been produced by arti- 

 ficial selection (and so that animal types are thus far 

 changeable) than that they are all the remnants of more 

 or less fantastic natural forms now as such extinct. If 

 the hypothesis of "Permanence" has to stand upon so 

 improbable a supposition as this, it is so far a less reason- 

 able hypothesis than that of " Evolution," and therefore 

 Darwin is justified in adducing the facts in question as 

 evidence of transmutation to this extent. 



But Mr. Pusey carries his criticism further than this, 

 and says : — 



" Granting that natural selection with spontaneous 

 variation could within the period of history develop out 

 of a rock dove a fantail, I do not see how we are any 

 nearer the conclusion that in ten times or a hundred 

 times that period these causes would develop the Goura 

 pigeon ; granting that, that a millionfold as much time 

 would evolve any of the true GallinaceJe." 



This way of treating the evidence is, however, hyper- 

 critical. It is certain that either "Permanence" or 

 " Evolution " is the truth, and therefore, if it were esta- 

 blished, or taken for granted, that within the historic 

 period selection is able so far to change an animal type 

 as toconvert a rock dove into a fantail, the presumption 

 becomes immense that in a hundred times that period the 

 operation of similar causes might develop a Goura pigeon. 

 Thus, in view of the supposed assumption or proof we 

 certainly arc " nearer the conclusion" in question than 

 we should be in the absence of a case analogous in kind 

 though not in degree. 



Similarly in dealing with the argument from affinity, 

 we think that Mr. Pusey is hyper-critical. He points to 

 the fact that crystals occur in natural systems, and that 

 their similarities cannot be due to genetic descent ; but 

 this analogy is clearly too lame to support any weight of 

 argument, and the same remark applies to his analogies 

 drawn from the similarities found in inorganic nature 

 generally. For in all these cases the similarities occur in 

 objects of far less complexity than organised structures, 

 and therefore the similarities are much less remarkable, 

 while in the case of organisms the known facts of heredity 

 furnish much the most probable explanation of the much 

 more complex similarities. This, perhaps, may most 

 briefly be shown by quoting the alternative hypothesis 

 which our author presents, for clearly it is one which no 

 man of the commonest judgment could for a moment 

 entertain. He suggests that systematic affinity may be 

 due to the resemblance between the chemical elements 

 (? and compounds) of which organisms are made up, and 

 adds what we must regard as a scarcely serious observa- 

 tion — " This hypothesis, though totally without positive 

 evidence to support it, is in itself quite as clear and 

 definite, and (what is called) explains the facts about as 

 well as the hypothesis of evolution." 



