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73 



THURSDAY, NOVEMBER 23, 1905. 



ZOOLOGY OF THE VERTEBRATA. 

 .1 Student's Text-book of Zoology. By Adam 

 Sedgwick, M.A., F.R.S. Vol. Li. Pp. xv + 705; 

 illustrated. (London : Swan Sonnenschein and Co., 

 Ltd. ; New York : The Macmillan Company, 1905.) 

 i'i ii e 21s. 



THE first volume of this " Student's Text-book of 

 Zoology " was published in 1S98, and dealt 

 with the invertebrate animals except echinoderms 

 and arthropods. It was then hoped that another 

 volume would suffice to complete the book, but that 

 sanguine estimate was far off the mark. After half a 

 dozen years the second volume has been completed, 

 thicker than the first by a hundred pages, and the 

 echinoderms, arthropods, enteropneusts, and tuni- 

 cates are still to follow. A fourth volume will be 

 required to deal with the principles of zoology. By 

 that time the so-called student's text-book will require 

 another title. 



The first volume has a well deserved reputation for 

 accuracy, clearness, terseness, and independence, and 

 in the crowd of text-books it has filled a definite place 

 to the satisfaction of teacher-, as well as of students. 

 Presupposing a knowledge of " types," it dealt with 

 tin- various classes in a systematic way, giving de- 

 tailed classifications and taking account of a very 

 large number of important forms. It was a successor 

 ol Claus's " Lehrbuch," but stronger in its grip, and 

 vastly more interesting. The second volume is like 

 unto the first, and it has been worth waiting for. 



Alter a short introduction on Chordata, the author 

 deals with the lancelets ; then follows a discussion of 

 the general characters of Craniata, and so on through 

 the vertebrate series, each class, subclass, and order 

 having its definition and general exposition followed 

 bv small print dealing with families and genera. The 

 definitions are models of terseness; the large-print 

 discussions of general characters are marvels of con- 

 densation and selective insight — almost peptonised 

 extract of zoology — and the small print is monumental 

 in its erudition. \Ye took the last four vertebrates 

 that happened to come into the laboratory — a water- 

 shrew, a golden-crested wren, some young fierasfers, 

 a specimen of Palaeospondylus — and for three out of 

 this fortuitous four we found interesting information 

 in this encyclopaedic volume. There is, however, 

 another side to this relative exhaustiveness, that the 

 details of classification are apt to change rapidly, and 

 that many of the implied systematic conclusions must, 

 from the nature of the case, have been simply accepted 

 by the author because they were well vouched for 

 by specialists. But there does not seem to be any 

 way out of this except refraining from the very de- 

 tailed treatment which is part of the characteristic 

 aim of the book, or else adopting the cooperative 

 device, which is apt to mean a lack of unity. It says 

 much for the energy of the author that the classifi- 

 cation of teleostean fishes is substantially that worked 

 out by Mr. Boulenger, who supplied proofs of his 

 work before its publication. 

 NO. 1882, VOL. J$] 



Leaving the question of the desirability of attempt- 

 ing so great exhaustiveness in what is at least called 

 a student's text-book — a question which the gratefully 

 recognised utility of the first volume has in part at 

 leasl answered- we venture to express the hope that 

 the final edition of the whole work will see some 

 re-arrangement. Even unconsciously the student has 

 what Herbert Spencer called an " architectonic " 

 instinct ; he likes some semblance of evolutionary 

 order in his text-book. But although Mr. Sedgwick 

 allows that enteropneusts and tunicates are chordates, 

 thev are not discussed in this volume, but must 

 eventually be treated, we presume, at a remote 

 distance, remote even from Amphioxus. Similarly, 

 the annelids will be far away from the arthropods, 

 and other instances might be given which suggest 

 that the conditions of the production of this great 

 work have not favoured its architectural plan. 



Another carping criticism which we must make is 

 this, that whereas the preface, like so many other 

 pic laiis, holds out the promise of "dealing fairly" 

 with habits as well as with morphological aspects, 

 we find after all that we have to be grateful for 

 small merries. 



We confess also to some disappointment at the 

 severity of Mr. Sedgwick's scientific mood, which 

 may he illustrated, fur instance, by this sentence: — 



" As to its (the group Mammalia) origin in evolu- 

 tion we have nothing to say lor the very good reason 

 that there are no facts by which we can arrive at 

 an\ conclusion on the subject." 



(This does not, of course, refer to the affinities 

 between Mammalia and other classes of vertebrates, 

 which are briefly discussed.) Similarly, it is very 

 difficult to discover what positive view, if anv, the 

 author holds in regard to the affiliation of Chordata 

 to an antecedent stock. Incidentally, the author lifts 

 just a little the veil with which he so successfully 

 conceals his evolutionist convictions. Thus he says 

 of the hag-fish : — 



" To hold that a free-living animal, and a 

 myxinoid must after all be regarded as such, can lose 

 its eyes through disuse would seem to be an impossible 

 position." 



\A'ith such useful things to say the author might, 

 to the advantage of his readers, have lifted the veil 

 rather oftener. Criticisms like that of the story of 

 the pedigree of horses are refreshing and salutary, 

 and we regret to learn from the preface that the 

 author has deleted a number of them. We look for- 

 ward to the fourth volume to reveal more fully the 

 author's scepticism " as to the value of some hypo- 

 theses widely held as to the course of organic evolu- 

 tion." It need hardly be said that Mr. Sedgwick is 

 "a convinced evolutionist"; he also believes in the 

 importance of natural selection, even in regard to 

 non-living things; but " as to the origin of the mani- 

 fold properties of living matter we know nothing. 

 The Darwinian theory did not account for properties ; 

 it left their origin to an imperfectly understood inter- 

 action between the organism and the environment, 

 and further than this we cannot at present go." 



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