July 21, 1892] 



NATURE 



267 



and such a discussion, though independent of optics, 

 would be certain to have important applications in it, be- 

 cause its results would often still apply when translated 

 into language of the electro-magnetic theory. The mathe- 

 matical investigation of vibrations might be made more 

 clear and definite when it is freed from the necessity of 

 adapting itself to experimental verification. 



Chapter xviii. is a useful one, dealing with " theories 

 based on the mutual reaction between ether and matter," 

 but we might have wished for a more satisfactory intro- 

 duction to the electro-magnetic theory that is given in 

 the last two chapters. The way in which the subject is 

 approached may illustrate some of the remarks made in 

 the beginning of this review. There is no doubt a very 

 serious difficulty in explaining the fundamental notions 

 underlying the theory, and Mr. Basset, instead of making 

 an attempt to help the student over the difficulty, sud- 

 denly plunges into a series of equations, referring us to 

 Maxwell's book for an explanation even of his symbols. 



We have perhaps given an inadequate idea of the 

 contents of Mr. Basset's book, which no doubt lends 

 itself to criticism from the physicist's point of view, but 

 which nevertheless fills a gap and possesses merits which 

 will render it of great value to the student of optics. 



Arthur Schuster. 



THE APODID/E. 



The ApodidcB : a Morphological Study. By H. M. 

 Bernard, M.A. Cantab. (London : Macmillan, 1892.) 



THE title of this little book is misleading. It is not a 

 treatise on the Apodidae, but a statement of the 

 author's speculations on the relations of the Phyllopodous 

 Crustacea and Branchiate Arachnida to the Chaetopod 

 Worms. The new observations recorded are few, and 

 the most important, that as to the presumed herm- 

 aphroditism of Apus cancriformis, quite insufficiently set 

 forth, and, so far as can be judged from the author's 

 meagre statement, erroneous. 



Mr. Bernard appears to be completely misinformed as 

 to current views on the relationships of Apus to other 

 Crustacea, and of that group, through it, to the parapodi- 

 ate worms. Apparently he addresses himself to a lay 

 audience, and poses, to start with, as the discoverer of 

 a new and unsuspected agreement between the lower 

 Crustacea and the Chastopoda. This may serve to excite 

 the interest of uninstructed readers, but the zoologist 

 knows that such pretensions are due either to defective 

 acquaintance with the subject or to a want of candour on 

 Mr. Bernard's part. The arguments by which Mr. 

 Bernard endeavours to support his thesis are, many of 

 them, those which have been effectively used by his pre- 

 decessors in the same cause ; others are new and re- 

 markable only for their arbitrary character and the 

 evidence which they give of the author's boldness in 

 writing a book on a morphological problem. Mr. 

 Bernard draws attention to the absence of developed 

 articulations in the limbs of Apus as giving them a re- 

 semblance to the parapodia of Chaetopoda. He states 

 that this absence "has already been pointed out by 

 Lankester and others, but its true s ignificance does not 

 seem to have been noticed." This is an incorrect allu- 

 NO. I 186, VOL. 46] 



sion to my essays on the appendages and nervous system 

 of Apus \q. J. Micr. Set., 1881), and on Limulus an 

 Arachnid {ibid.), which is the more to be regretted since 

 they appear to have furnished Mr. Bernard with such of 

 his theories as well as his facts as will bear examination. 

 At p. 368, loc. cit., my statement runs— 



"I have long been of the opinion which Prof. Claus 

 appears to hold, that the appendages of the Arthropoda 

 are homologous (or, to use a more distinctive term, 

 ' homogenous ') with the appendages of the Chaetopoda, 

 and on this account I consider it a proper step in classifi- 

 cation to associate the Cheetopoda with the Arthropoda 

 and Rotifera in one large phylum— the Appendiculata." 



Yet Mr. Bernard comes forward to tell us that he now 

 for the first time draws attention to the true significance 

 of the absence of articulations in the limbs of Apus, 

 although (as he admits) this condition was especially 

 noted and very carefully described eleven years ago by 

 me in the same essay in which the above paragraph as 

 to the relationship of Arthropoda and Chaetopoda occurs. 

 This is a sample of Mr. Bernard's method of claiming 

 novelty for what he has to say when dealing with old 

 materials. Frequently he asserts in strong language 

 novel propositions which are purely speculative and of 

 the truth of which no evidence is adduced. There is in 

 no part of this little book any evidence that the author has 

 made use of living- or of well-preserved material, or has 

 had any special opportunities of studying the genera and 

 species of Apodidae ; nor does it appear that he has any 

 experience as a zoologist which might give some weight 

 to his fanciful conceptions. On the contrary, these crude 

 speculations and dogmatic assertions are his first original 

 contributions to zoological literature. I regret to be 

 obliged to say that in my opinion (which I am called 

 upon to express candidly in these pages) "The Apodidae" 

 is not a book which can be recommended either as a 

 repository of fact or as a model of the method in which a 

 morphological problem should be attacked. 



E. Ray Lankester. 



OUR BOOK SHELF. 



Anatomy, Physiology, Morphology, and Development of 

 the Blow-fly {Calliphora erythrocephala). Part IIL By 

 B. Thompson Lowne, F.R.C.S., F.L.S. (London : R. 

 H. Porter, 1892.) 



We have before us another section of Mr. Lowne's 

 work, which has grown upon the author's hands, and will 

 form two volumes instead of the one originally intended. 

 Part iii. is occupied with the internal anatomy of the 

 imago, embryonic development, histology, and the de- 

 velopment of the imago. On each of these heads a great 

 amount of information is supplied, and the author's 

 statements are illustrated by many figures. As to the 

 puzzling question of the way in which the alimentary 

 canal of the blow-fly is developed, Mr. Lowne holds an 

 opinion which is probably shared with no second person. 

 What Voeltzkow and Graber take to be the proctodasum, 

 and what Korscheltand H eider believe to be the amniotic 

 cavity, Mr. Lowne calls archenteron. He is content, as 

 he tells us in his preface, to await the verdict of posterity 

 on such conclusions as this. We are content to wait too. 

 The subject is too difficult for full consideration in this 

 place, and it would be unfair to express a strong opinion 

 without ample discussion of the evidence. It is not un- 

 fair, we think, to characterize many of Mr. Lowne's 



