4 I2 



NA TURE 



\_August 30, 188S 



while his mental development is very far inferior ;— so that, as 

 Wallace remarks, " the idea is suggested of a surplusage of 

 power; of an instrument beyond the wants of its possessor." 

 And if it is true, as I believe it is, that the brain of savage man 

 finds its special activity in the formation and use of language, 

 this does not solve but only transforms the difficulty ; for 

 language itself must in prehistoric times have attained a develop- 

 ment far in advance of the intellectual wants of those who formed 

 it, because the same languages, with comparatively few additions 

 to the vocabulary and no further grammatical development, still 

 suffice for the wants of their civilized descendants ; whereas, on 

 Darwinian principles, language could not be evolved beyond the 

 intellectual needs of those speaking it. 



There are also many cases in the lower creation where struc- 

 ture appears to have been developed, not as the result of 

 function but in anticipation of function ; just as a ship is built on 

 the land for the purpose of afterwards floating on the water. 

 I cannot occupy your space with details of these, but will 

 enumerate those of which the evidence seems tolerably distinct. 

 All the Hydrozoa are probably descended from a form re- 

 sembling the Hydra, between which and the Medusae there is a 

 gradation, though not quite unbroken. Once the Medusa is 

 produced and swims away from the plant-like stem that bore it, 

 its powers of wandering, and dispersing its eggs widely, will give 

 its species a great advantage in the struggle for existence. But 

 how can any natural selection effect the evolution of the Medusa 

 while it is still imperfect, and sheds its eggs without leaving the 

 parent stem ? 



M tiller, in his " Facts for Darwin," says of the transition from 

 the Zoea to the Mysis form in the metamorphoses of a species of 

 Peneus, or prawn, that "the long abdomen, which just before 

 was laboriously dragged along as a useless burden, now, with its 

 powerful muscles, jerks the animal through the water in a series 

 of lively jumps." The Nauplius, which is the form in which 

 this Peneus leaves the egg, has no abdomen ; this is acquired 

 when the Nauplius develops into a Zoea, and consists of 

 segments which appear between the body and the tail of the 

 Nauplius. Midler's account seems to show that this abdomen is 

 developed before it is useful to the animal, and for the purpose 

 of becoming useful further on in its development. It is to be 

 observed that in this case, as in that of the Medusa, the 

 entire evolution goes on amid the same surroundings : unlike the 

 case of Batrachia and most insects, there is no change of the 

 conditions of life to accompany the transformation and to help 

 to account for it. The same remark applies to the development 

 of the star-fish out of the Bipinnaria, and of the sea-urchin out of 

 the Pluteus — two of the most wonderful metamorphoses known. 

 The development of the lungs of the Balrachian out of the 

 swim-bladder of the fish is an adaptive modification, and presents 

 no special difficulty. But in the cellular and spongy texture of 

 the swim-bladder of many Ganoid fishes, there appears to be a 

 preparation for future transformation into lungs. This, however, 

 is a point on which it would not be right to lay much stress. 

 But it is different with the development of the fin of the fish into 

 the leg of the Batrachian. The intermediate state appears to be 

 preserved in the fin-rays — -we can scarcely call them fins — of 

 Lepidosiren. The single fin-ray of Ceratodus has in Lepidosiren 

 lost its membrane, and consequently become inefficient as a fin, 

 without being in any degree efficient as a le^, or acquiring any 

 vestige of a foot ; such a change cannot be beneficial to an 

 animal which is still a fish and lives a fish's life ; it can be inter- 

 preted, so far as I see, only as a preparation for the ultimate 

 development of feet and legs. This development, however, does 

 not appear to have been actually attained by any descendant of 

 Lepidosiren ; for its scaly covering, and the peculiarity of its 

 nostrils, go far to forbid the supposition that the Batrachia can 

 be its descendants. 



Another instance of the same kind is that of those Ascidian 

 larvre which are the probable origin of the Vertebrata. Of 

 what use can the dorsal groove and the notochord be to those 

 minute and lowly organized animals themselves? They appear 

 capable of interpretation only as the preparation for a vertebral 

 column and a spinal cord to be afterwards evolved. But the 

 strongest instance of the kind which I know of, except that of 

 the brain of man, is the existence of pneumatic bones (that is to 

 say, bones hollowed out for lightness, like those of flying birds) 

 among Dinosaurians (see Prof. Cope's paper on Megadactylus 

 probyzelus ?.s reported in Nature, vol. i. p. 347). The re- 

 semblances of the skeleton appear to prove that birds must 

 be descended from Dinosaurians. No Dinosaurian had the 



power of flight, yet here is a character useful oily to flying 

 animals, and interpretable only as a preparation for a power of 

 flight to be afterwards evolved. 



Were a competent anatomist and morphologist to search for 

 them, the entire organic world would probably be found to be 

 full of such instances of what I call structure in anticipation of 

 function. Joseph John Murphy. 



Belfast, August 22. 



It is evident from the letter of the Duke of Argyll under this 

 heading in your issue of August 9 (p. 341). that he has alto- 

 gether misconstrued some of the main biological principles 

 which Darwin promulgated ; and it also appears as if the entire 

 neglect of certain important items which received due consider- 

 ation in the " Origin of Species" is either done with purpose, 

 or else is simply an effect of obscuration. In either case, the 

 fallacious interpretation may be due to the polemical style in 

 which his Grace is usually wont to distinguish himself, and the 

 strong bias imported into the treatment has«rendeied a true 

 representation of the conclusions he assails altogether impossible. 

 Exception must be taken to the very setting forth of the pre- 

 mises of the Duke's argument. "Sometimes," he says, the 

 organs "are called 'aborted,' sometimes 'degenerated,'" &c. 

 This certainly is so for no less a reason than that sometimes 

 they «;vaborted, while at other times they are "representative," 

 or sometimes, again, they are incipient organs. So variously, 

 indeed, are the organs affected, that Darwin found it in some 

 cases extremely difficult to pronounce respecting them. 1 The 

 uninitiated in the subject would naturally infer, from the letter 

 in question, that Darwin had never devoted any of his pages to 

 the discussion of those organs which he generally spoke of as 

 "nascent"— a term which the Duke, for the purposes of his 

 argument, ignores. There is, moreover, nothing in any way 

 new suggested by him in his communication. 



The special case referred to, for instance, is simply one of the 

 difficult problems which Darwin set himself, in the "Origin of 

 Species," to solve, and respecting which he concluded, from his 

 knowledge of all the facts then available, that "as we know 

 nothing about the habits and structure of the progenitors of the 

 existing electric fishes [of the various non-related types dealt 

 with], it would be extremely bold to maintain that no service- 

 able transitions are possible by which these organs might have 

 been gradually developed" ("Origin," sixth edition, p. 150). 

 Whilst in the "Descent" a long section is devoted to the 

 citation of instances of homologous rudimentary structures in 

 man. and functionless organs generally are amply treated upon 

 elsewhere — compare the various references in " Variation," and 

 also "Origin" (pp. 108-12). In some instances they are deter- 

 mined to be vestigial, though for the most part they can only 

 be so recognized in their ancestral relation. 



Although Prof. Ray Lankester, in his interesting chapter on 

 "Degeneration" ("Nature Series"), aptly remarked, " We have 

 as possibilities either balance, or elaboration, or degeneration," I 

 am inclined to think — in agreement, probably, with the Duke — 

 that in that paper perhaps too much weight was attached to the 

 last-named process. Perhaps it was due to the expressed desire 

 of calling attention to Dr. Dohrn's treatise on the subject ; but, 

 after all, it is simply a view that is taken respecting certain 

 important facts, and whether an organ in a transitional state is 

 progressing or retrogressing is a matter which relates chiefly to 

 time, and does not invalidate the fact of the change that is in 

 process of evolution. It has not, however, been satisfactorily 

 proved, so far as I can find, that the limited digitation in Bipes 

 and Seps is the result of atrophy, as decidedly stated by Prof. 

 Lankester ; but as I am uninformed respecting the ontogeny— 

 upon which everything depends— of these reptilian forms, I 

 may be wrong in questioning this point. 



Instances of transitional and incipient organs, rare though they 

 may be, have, therefore, been fully considered by Darwin in his 

 volumes ; but we may, speaking more generally, truly say that 

 the entire development hypothesis is a recognition of the 

 structural deformation of nascent organs, which are ever being 

 reconstituted, mainly in a progressive direction. The dimculty 

 of actually observing an organ in process of development 

 was acknowledged by Darwin to be considerable, partly on 

 account of the slow rate of progression, and partly because 



1 '-It is often difficult to distinguish between rudimentary and nascent 

 organs; for we can judge only by analogy whether a pare 1; capab.e of 

 further development, in which case alone it deserves to be called nascent 

 "Origin," sixth edition, p. 398). 



