August 27, 1908J 



NA TURE 



387 



The book suffers from want of compression, and 

 there are some repetitions. The long chapters on 

 the geographical aspects of the problem serve rather 

 to show how little help must be expected from that 

 line of inquiry until much more minute treatment can 

 be applied. No one supposes that any fresh lesson 

 of importance is to be derived from the broad facts 

 of geographical distribution, and the deductions that 

 have been already drawn could, in so far as they are 

 of consequence, be amply stated in half a dozen pages. 

 On the other hand, as to the more interesting pheno- 

 mena of geographical inter-relationship, the problems, 

 for instance, of intergrading species, too little is said. 

 In a text-book of this scope it would have been well 

 to direct the attention of students to the necessity for 

 thorough study of facts of this class, a field in which 

 there is room for much analytical research. 



There is one rather serious omission. The pheno- 

 mena of regeneration and the mechanics of develop- 

 ment are among the most obscure with which a theory 

 of descent has to cope. In the minds of many evolu- 

 tionists, the existence of those strange and specific 

 powers of response to injury which modern research 

 has revealed constitutes a formidable problem, and 

 though for its solution we still wait, the facts should 

 have been stated. 



In dealing with matters of opinion, Prof. Lotsy 

 shows good judgment and critical power. This is 

 especially manifested in his discussion of adaptation, 

 of the evidence for mutation, and of the assertions by 

 which an attempt has been made to revive Lamarckian 

 views. Sometimes, perhaps, one is conscious of an 

 exaggerated patience. Conventional arguments which 

 the author plainly recognises as bad are repeated out 

 of deference to their originators. The expert is not 

 in doubt as to his real opinion, but the lay reader will 

 carry away the impression that decided questions are 

 still open. When he deals with the writings of 

 Wallace, indeed, he allows himself the remark that 

 this is " Selectionstheorie a outrancc," but such 

 freedom of expression is rare. 



The author gives a full but somewhat non-committal 

 account of the views of Eimcr, and discusses the rela- 

 tion of Nageli to the conception of orthogenesis as 

 a main factor in evolution. Yet, after reading- all 

 that is said on this question, it is not easy to seize 

 the exact point which is relied on as a proof of the 

 reality of orthogenesis. The adaptation mav be very 

 perfect, and selection of indeterminate variations an 

 unpromising account of the origin of that perfection, 

 but it will never do to attribute this wonderful power 

 of orthogenetic variation to organisms simply because 

 we do not see how they could have become what they 

 are without it. This, apparently, is Prof. Lotsy'sview 

 also, but many would have been glad of a more de- 

 finite lead. 



If the book reaches a second edition, as it probably 

 will, the question of reducing it to two-thirds its 

 present size should be considered. In that event also 

 the proofs should be submitted to a professional proof- 

 reader, for in this second part, as in the first, the 

 abundance of typographical slips exceeds all reason- 

 able limits. ' W. Bateson. 



NO. 2026, VOL. 7SI 



METALLOGRAPHY. 



Introduction to Metallography- By Dr. Paul Goerens. 

 Translated by Fred Ibbotson. Pp. x-l-214; illus- 

 trated. (London : Longmans, Green and Co., 

 lyoS.) Price ys. 6d. net. 



ALTHOUGH metallography is a very j'oung 

 science, a number of little books on it have 

 already made their appearance, and of these Dr. 

 Goerens's " Einfuhrung in die Metallographie " is not 

 the least successful. The author says in his preface 

 that before the publication of his work the numerous 

 papers on the subject had not undergone systematic 

 collection in Germany. If it is not the only book in 

 this country, it is nevertheless welcome, and Mr. 

 Ibbotson 's excellent translation greatly increases its 

 usefulness. 



Alloys can be studied in several ways, of which the 

 most important have been found to be the prepara- 

 tion of their cooling curves and the examination of 

 polished and etched specimens under the microscope. 

 The whole book is devoted to these two methods, and 

 no reference is made to the electric and heat con- 

 ductivity of metals and alloys, to their density, hard- 

 ness, malleability, ductility, colour, resistance to 

 shock, &c. No doubt this is due to the small 

 amount of systematic investigation that has been 

 devoted to these properties, but when a complete work 

 on metallography is written these points cannot be 

 entirely ignored. 



However, the preparation of cooling curves by the 

 use of thermocouples is adequately described by the 

 author, and the various means of detecting critical 

 points explained clearly. There is not much discus- 

 sion of pyrometers, and the platinum resistance pyro- 

 meter, with which Heycock and Neville did their clas- 

 sical work, is not mentioned, presumably because it is 

 not much used in Germany. 



Physical mixtures, or bodies of perfectly uniform 

 composition not governed by the laws of valency, are 

 divided by Dr. Goerens into aqueous solutions, fused 

 salts and alloys. He defends this use of the histori- 

 cal method on account of its expediency, observing 

 that the reader will find out for himself as he proceeds 

 that the division is arbitrary. The author, however, 

 soon reaches the alloys, and thereafter for seventy- 

 five pages gives a valuable account of the existing 

 views on their constitution. This part is illustrated 

 by descriptions of a number of series of binary alloys 

 drawn from work on cooling curves done in England, 

 Germany, and France, and the references are 

 numerous and accurate. So many examples 

 are given in each subdivision that it is a 

 pity that here at least completeness was not 

 attempted by including all the binary alloys 

 which have been worked out. The additional 

 space required in a second edition would not be great, 

 and the author would produce a book of reference 

 without destroying its usefulness as an introductory 

 volume for students. There seems no reason to 

 exclude even the mixtures of metals with oxygen, 

 sulphur, arsenic, S:c., many of which have been 

 studied bv Friedrich. These series of bodies are of 



