554 



NA TURE 



[April i6, 1896 



to be useful. But the general question is not affected by 

 the supposition that advantageous variations may be 

 sometimes minute. Minute or great, they have to be 

 assumed in the argument for selection ; and whether 

 minute or great, they have a definite cause." 



This very ingenious argument is well calculated to 

 impress those readers of Prof. Cope's book who have 

 no other sources of information that natural selection is 

 quite a subsidiary agent in causing evolution, and that — 

 as he says in his concluding paragraph — " the stimuli of 

 chemical and physical forces and also molar motion, or 

 use, or its absence, are abundantly sufficient to produce 

 variations of all kinds in organic beings." 



But they can produce this effect only on the assumption 

 that all the modifications so produced in individuals are, 

 partially at least, transmitted to their offspring ; while 

 those very numerous cases in which essential characters 

 could not possibly have been produced by the causes he 

 suggests, are entirely unnoticed. Such are all those 

 curious structures which are only used once in a life- 

 time ; those whose only function is to alarm enemies ; 

 most of the protective forms, motions, and colours of 

 insects, as illustrated in the stick and leaf insects, or in 

 those which are deceptively like moss, or flowers, or the 

 dung of birds ; the poison-fangs of snakes and the 

 stench-glands of skunks, and innumerable other examples 

 which will occur to every naturalist. Note, too, how "aj' 

 a cause'''' 'vs\ the first quotation is changed immediately 

 afterwards to " the primary cause," and the implication that 

 we believe natural selection to be the " origin of variation " 

 and " the cause of the alternatives from which it selects," a 

 theory for which Prof. Cope never states his authority, 

 and which, so far as I know, has never been even 

 suggested, except by incompetent or careless reviewers. 

 Strange to say we have the acknowledgment that " minute 

 advantageous differences will secure survival," but it is 

 followed by the proviso that " the variations which con- 

 stitute evolution have been in a vast number of cases too 

 minute to be useful." This, I suppose, means that the 

 changes produced by external causes in the individual are 

 too minute to be useful till transmitted and accumulated 

 by inheritance. Whether that is so or not, no evidence 

 whatever has been adduced ; while abundant evidence 

 exists in the works of Prof Cope's own countrymen, and 

 in the measurement of many hundreds of specimens of 

 common species in this country, that normal variability is 

 not minute but very large, and that this variability ex- 

 tends to every part and structure, and to every external 

 and internal organ when search has been made for it. 

 That such well-known facts as these should be entirely 

 ignored, and the extraordinary and wholly unprovable 

 statement made, that the variations which constitute 

 evolution "have been in a vast number of cases too 

 minute to be useful," seems to show that the advocates 

 of Neo-Lamarckism feel that they have a very bad case. 

 In the third part, on the inheritance of variation, we 

 expect to find some experimental facts bearing on the 

 question at issue. But I can only find assumptions and 

 opinions. Breeders of animals, it is said, all believe in 

 the inheritance of the results of nutrition and exercise, 

 and pages are given to prove such beliefs ; and after 

 describing the evolution of the American trotting-horse, 

 Prof. Cope says : 



NO. 1381, VOL. 53] 



" Viewed as phenomena, there is every appearance 

 and indication that the changes acquired by individuals 

 through the exercise of function have been to some 

 degree transmitted, and have been cumulative, and that 

 this has been one factor in the evolution of speed." 



However unsatisfactory is the author's treatment of 

 the evidence for the doctrine which forms the main 

 subject-matter of the book, we did not expect that he 

 would repeat the absurd argument which Lord Salisbury 

 used at Oxford, and which has been so destructively 

 criticised by Herbert Spencer. Yet in the chapter on 

 "The Energy of Evolution" he gives, among the 

 " weighty considerations " showing that natural selection 

 cannot be the cause of the origin of new characters, the 

 following statement : 



(3) " In order that a variation of structure shall 

 survive, it is necessary that it shall appear simul- 

 taneously in two individuals of opposite sex. But if 

 the chance of its appearing in one individual is very 

 small, the chance of its appearing in two individuals is 

 very much smaller. But even this concurrence of 

 chances would not be sufficient to secure its survival, 

 since it would be immediately bred out by the immensely 

 preponderant number of individuals which should not 

 possess the variation." 



Whence of course it follows, that without the 

 Lamarckian factors to produce the right variations at 

 the right time, natural selection is powerless, as it will 

 have nothing to select from ! It really seems incredible 

 that after nearly forty years' discussion of evolution and 

 natural selection such an argument as that here quoted 

 can be set forth in a serious book by a life-long teacher 

 and worker in the field of biology. 



It is refreshing to turn to Mr. Archdall Reid's volume 

 which, though unnecessarily diffuse, is full of original 

 ideas and acute reasoning. The larger part of it is 

 devoted to a discussion of the general subject of organic 

 evolution. This is exceedingly well done, and it contains 

 a very forcible argument against the possibility of the 

 inheritance of acquired characters in the higher animals, 

 derived from the facts of cell-division and specialisation 

 in the development of the individual. This argument has 

 not, within my knowledge, been so clearly and forcibly set 

 forth by any other writer. There are also some very acute 

 criticisms of the writings of Herbert Spencer and others 

 on evolution, and great stress is laid on a rather neglected 

 subject, the development of acquired characters during 

 the growth of the individual, though on this point the 

 author's views seem rather exaggerated and open to 

 criticism. The latter portion of the book, which gives the 

 title to the work, though original is somewhat dis- 

 appointing, as it is entirely limited to evolution against 

 disease. The author argues that this is effected solely 

 by natural selection, and in the facts presented by the 

 various amounts of resistance of different races to certain 

 zymotic diseases he finds another powerful argument 

 against the Lamarckian theory. He maintains that there 

 is no such thing as hereditary disease, but only hereditary 

 tendency to contract the disease. He traces most of the 

 zymotic diseases to the unhealthy crowding that is uni- 

 versal in civilised communities, and he has some very 

 strong remarks on the way in which our false civilisation 

 is exterminating so many of the lower races. One of 



