246 



NA TURE 



[January 12, 1899 



LETTERS TO THE E DTI OR. 



[TAe Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of Nature. 

 A'o notice is taken of anonymous communications.'^ 



The Utility of Specific Characters. 



In a recent issue of the Journal of the Linnean Society 

 (Zoology, No. 172) there is a short paper by my friend Dr. 

 St. George Mivart, in which he gives numerous cases of species 

 of Lories peculiar to various Papuan or Pacific Islands, which 

 differ in some details of coloraticm from allied species in other 

 islands, while they are usually altogether unlike the other birds 

 inhabiting the same island. He then argues, as Captain Hutton 

 had done with regard to similar jihenoniena among the fruit 

 pigeons of the genus Ptilopus, that these various specific mark- 

 ings cannot be useful, and especially that they cannot be needed 

 as "recognition-marks," because the whole coloration of the 

 genus is so distinct that they cannot possibly be confounded 

 with any other birds now inhabiting the same islands. He 

 therefore concludes that these facts "are fatal to a utilitarian 

 explanation of the orijjin of all specific characters." At the same 

 time he accepts evolution and the natural biological origin of 

 these and all other characters. These conclusions appear to me 

 to be wholly illogical and to be reached by omitting to take 

 account of the fundamental idea of organic evolution itself, 

 namely, that each species has been, somehow, developed from 

 an allied but distinct species, living or extinct. I therefore ask 

 leave to point out how this omission affects the problem. 



It is quite clear then that each distinct species of lory or fruit 

 pigeon now found isolated from their allies in so many of the 

 Pacific Islands must (if evolution is admitted) have originated 

 by modification from some other parent species. The modifi- 

 cation may have occurred in another island (or continent) or in 

 the island in which the modified species now exists ; but, in 

 either case during the process of differentiation, recognition- 

 marks would be of vital importance by checking intercrossing, 

 .so much so that it is doubtful whether in many cases the 

 required structural or physiological modifications could be 

 brought about without them. I do not remember that this pro- 

 position has been seriously denied, and it is the omission to 

 take account of it that invalidates the argument of Dr. Mivart 

 and Captain Ilutton, founded upon the existing distribution of 

 the species in question. 



Perhaps these gentlemen will reply that they hold the views 

 of Romanes and Gulick, that the specific difi'erences in question 

 are the direct result of the action of changed conditions on the 

 progeny of the individuals which fir.st reached the islands ; but 

 this theorj- is a pure assumption in support of which I am not 

 aware that any adequate facts or observations have been adduced, 

 while such changes in a// the individuals exposed tu the influence 

 of the new conditions is entirely opposed to the known facts 

 of variation. Supposing, however, that the existing species 

 originated in the islands where they now occur by modification 

 of some two or more original immigrants, let us consider how 

 the change would be effected in accordance with the known 

 facts of variation and natural selection. 



The first thing that happens on the introduction of a new 

 form into an island well-suited to it, and with no other 

 enemies than those to which it is already adapted, is to increase 

 rapidly till the island is fully stocked— witness the rabbit in 

 Australia, New Zealand, and Porto Santo, the sparrow in 

 America, and numerous other cases. But as soon as the island 

 is fully stocked and all future increase dies off annually, natural 

 selection begins its work, and the least adapted to survive, in 

 every stage from the egg to the parent birds, get destroyed by 

 .some means or other. Now, if this process of elimination is 

 identical in character with that to which the species was sub- 

 jected in its former home no specific change will lake place, 

 because the whole structure and habits which constituted 

 "adaptation to conditions" in its former habitat are equally 

 effective in its new abode. But if there is any diflference in the 

 environment which requires a new adaptation, whether as regards 

 food, seasons, diseases, or enemies of other kinds, then natural 

 .selection will certainly tend to bring about that new adaptation, 

 and as in such a limited area local segregation will be ineffective, 

 some external indication, marking off the new and better 

 adapted from the old less adapted type, will be of the first im- 

 portance in the prevention of inter-crossing and thus hastening 



NO. 1524, VOL. 59] 



I he process of complete adaptation ; and these external indica- 

 tions are what I have termed '■ rccognition-maiks." When the 

 new type is fully established and the old parent-form has died 

 out, the work of these recognition-marks will have been done ; 

 but having been established by a severe process of selection 

 they have become fixed and continue to form the "specific 

 character" distinguishing the new from the old species. The 

 repeated statement of Dr. Mivart, that in this or that case the 

 peculiar marking cannot be a recognition-mark, or that such 

 "recognition-marks" are quite needless, is therefore beside the 

 question, since the very existence of the new species during the 

 process of different i.ition may have depended upon them. 



I have here confined myself strictly to the one point raised by 

 Dr. Mivart and Captain Hutton, having already dealt with the 

 general question of " utility " elsewhere. 



Ai.i RED K. Wai lace. 



The Duke of Argyll and Mr. Herbert Spencer. 

 In his review of the Duke of Aigjll's "Organic Evolution 

 Cross-examined, tVc. ," Prof. Meldola describes the Duke as 

 " doing violence to Huxley's teaching," and asks him " in 

 fairness" to " reperuse" something Huxley has written. After 

 recognising the unfairness he refers to, he might not unfitly 

 have suspected unfairness in the Duke of Argyll's represent- 

 ations of my views : especially considering the absurdities as- 

 cribed to me. Yet Prof. Meldola says that the Duke " makes 

 some good points out of Mr. Spencer's change of view with respect 

 to the eflSciency of natural selection," and represents him as 

 making merry " over Mr. Spencer's al>andonment of that ex- 

 cellent child of his creation, the term ' survival of the fittest.' " 



Had Prof. Meldola looked into the matter, he would have 

 found that I have in no degree whatever abandoned the term 

 " survival of the fittest." The Duke of Argyll has misrepre- 

 sented me in a way which is extremely surprising. In the 

 " Factors of Organic Evolution " ("Essays," i. 429-30), after 

 pointing out that the metaphorical character of Sir. Darwin's- 

 expression "Natural Selection" is apt to mislead, as he him- 

 self admitted, I said that "kindred objections maybe urged 

 against the expression 'survival of the fittest.'" I said that 

 " survival " " suggests the human view of certain sets of 

 phenomena " rather than the view of them as physical facts ; 

 and I further said that " If a key fits a lock, or a glove a 

 hand, the relation of the things to one .another is presentable 

 to the perceptions. No approach to fitness of this kind is made 

 by an organism which continues to live under certain con- 

 ditions " (p. 430). But there is no admission that the words, 

 imperfectly adapted as they are, fail to express the truth in 

 question with approximate correctness. Any one who will turn 

 to the chapter on " Indirect Equilibration," in vol. i. of the 

 " Principles of Biology" (§ 164), will read .as follows : — 



" That is to say, it cannot but happen that those individuals 

 whose functions are most out of equilibrium with the modified 

 aggregate of external forces, will be those to die : and that 

 those will survive whose functions happen to be most nearly in 

 equilibrium with the modified aggregate of external forces. But 

 this survival of the fittest implies multiplication of the 

 fittest, &c." 



It was in this place and in this manner that the expression 

 " survival of the fittest "' arose, and to .show that I have 

 abandoned the lielief it formulates it is needful to show that I 

 have abandoned the theory of indirect equilibration which it is 

 used to express brietly. I have done nothing of the kind, and 

 there is no sign that I have done anything of the kind. 



I am, indeed, not a little astonished that the Duke of .-Argyll 

 should have reproduced these statements of his after the direct 

 contradiction given to them in my reply to him published in 

 the Nineteenth Century for February 1S8S. At the close ol 

 my article, entitled "A Counter Criticism," there occur tht- 

 sentences : — 



" On one further point only will I .say a word, and thi> 

 chiefly because, if I p.a.ss it by, a mistaken impression of a serious 

 kind may be diffused. The Duke of Argyll represents me as 

 ' Riving up 'the ' famous |>hrase,' ' survival of the fittest," and 

 wishing 'to abandon it.' He does this because I have pointed 

 out that its words have connotations against which we must be 

 on our guard, if we would avoid certain distortions of thought. 

 With equal propriety he might say that an astronomer abandons 

 the statement that the planets move in elliptic orbits, becau.se 

 he warns his readers that in the heavens there exist no such 



