NATURE 



553 



THURSDAY, APRIL i6, 1896. 



OLD AND NEW THEORIES OF EVOLUTION 

 The Primary Factors of Organic Ei'olution. By E. D, 

 Cope, Ph.D., Professor of Zoology and Comparative 

 Anatomy in the University of Pennsylvania. Pp. xvi + 

 532. (Chicago : The Open Court Publishing Company, 

 1896.) 

 The Present Evolution of Man. By G. Archdall Reid. 

 Pp. 370. (London: Chapman and Hall, Limited, 1896.) 



PROF. COPE tells us in his preface that his work may 

 be regarded as containing a plea on behalf of the 

 Lamarckian view of the factors of evolution ; and he 

 believes that evidence has now been accumulated to 

 demonstrate the doctrine, which, he says, he has defended 

 as a working hypothesis for twenty-five years. At p. 9 of 

 the introduction, he states, referring to one of his own 

 papers : '' By the discovery of the palasontologic succes- 

 sion of modifications of the articulations of the vertebrate, 

 and especially mammalian skeleton, I first furnished an 

 actual demonstration of the reality of the Lamarckian 

 factor of use, or motion, as friction, impact, and strain, 

 as an efficient cause of evolution." Such statements as 

 these lead the reader to expect that at last we shall have 

 something of the nature of proof of the inheritance of 

 acquired characters, and that the difficulties and objec- 

 tions of those who hold Weismann's views will be fairly 

 met and satisfactorily answered. 



The work is divided into three parts, headed respec- 

 tively : "The Nature of Variation," "The Causes of 

 Variation," and "The Inheritance of Variation." The 

 first part deals with variation, phylogeny, parallelism, 

 and catagenesis. Very full accounts are given of the 

 varieties that occur in some of the animals inhabiting the 

 United States, with special reference to climatal con- 

 ditions. Aridity is said to produce a blanching of colours, 

 while moisture produces intensity. Some groups increase 

 in size as they spread southward, others towards the 

 north, and this is connected with the centre of the area 

 of distribution being in the south or the north. We have 

 also a careful description of the progressive development 

 of several important groups as indicated by their fossil 

 remains, with a general outline of the phylogeny of the 

 mammalia ; while the chapter on parallelism deals with 

 the general correspondence between the course of 

 development of the individual and of the class or order 

 to which it belongs. 



At the end of this part of the volume, which has been 

 purely descriptive and has entirely avoided any reference 

 to natural selection or to the broader features of variation, 

 we find this extraordinary statement. 



"It has been proved, as it appears to me, that the 

 variation which has resulted in evolution has not been 

 multifarious or promiscuous, but in definite directions. 

 It has been shown that phylogeny exhibits a progressive 

 advance along certain main lines, instead of having been 

 indefinite and multifarious in direction." 



Of these two statements the latter is true, and has 

 been fairly proved by the facts which have been set 

 forth ; while the former is absolutely untrue, and if the 

 NO. I381, VOL. 53] 



facts which this volume sets before the student do not 

 show it to be untrue, it is only because they have been 

 selected and set forth in such a way as to illustrate the 

 theory that variations are in definite directions only. 

 For example, although Dr. J. .\. Allen is quoted largely 

 to show the variations of birds in definite directions in 

 accordance with changes of climate, nothing is said of 

 his more important work on " The Mammals and Winter 

 Birds of Florida," in which he has given detailed 

 measurements showing that all the commoner species 

 do exhibit " multifarious variations " which are also 

 "multifarious and indefinite in direction." He shows 

 that the total length, as well as the length of the wing, 

 the tail, the beak, and the feet, all vary simultaneously 

 but to a large extent independently. Further, he shows 

 that each of the primary wing feathers, and each of the 

 toes also vary simultaneously and to a large extent 

 independently. Other writers have shown that in 

 mammalia the skull and all its parts vary simultaneously; 

 while what is known of the variation of the muscles, 

 the nerves, the blood-vessels, the intestines, and other 

 internal organs, show that these even exceed the external 

 organs in the multifarious and indefinite character of 

 their variations. All this is the common knowledge of 

 every biologist ; yet we have a great authority and 

 experienced biological teacher, first omitting all reference 

 to these facts, and then declaring that he has /w7v^ that 

 they do not exist I 



Coming now to the second division of the book, we find 

 abundant evidence as to the changes effected in indi- 

 viduals by the action of various external causes, by far 

 the larger portion being devoted to a statement of the 

 supposed mechanical origin of the peculiar forms of the 

 teeth and bones in the vertebrata, illustrated by the 

 various lines of evolution made known by palaeontology, 

 and always assumed to be the result of use (or disuse) 

 and motion. Then follows a short chapter on natural 

 selection, which is described in the most cursorj' manner, 

 almost immediately diverging to sexual selection, to 

 which more space is given. We then have a single 

 paragraph devoted to protective modifications of colour 

 or form ; and the author here takes the opportunity of 

 dealing a blow at the Darwinians by first misstating 

 their views, and then demolishing his own misstatement. 

 He says : 



" Much is to be found of interest on this attractive 

 subject in the writings of Wallace, Poulton, Beddard, 

 and others. The two authors first named ascribe these 

 colour and form characters to natural selection as a cause. 

 This is, however, impossible ; yet natural selection has 

 undoubtedly been the cause of their survival." 



The italics are Prof. Cope's. He then goes on : 



"The first objection to the belief that natural selection 

 is the primary cause of organic evolution has already been 

 stated as follows: 'A selection cannot be the cause of 

 those alternatives from which it selects. The alternatives 

 must be presented before the selection can commence.' 

 But the supporters of the view that natural selection is the 

 origin of variation, allege that it produces this result by the 

 continual survival of minute differences which are useful, 

 thus accumulating variation. That minute advantageous 

 differences will secure survival no one can doubt, but it 

 must be re.nembered that the variations which constitute 

 evolution have been in a vast number of cases too minute 



H 1! 



