242 



NATURE 



[April 



j< I. 11)11 



vantafjcs and disadvantajjcs of paraftm and celloidin 

 as imbedding matorials. Around thfse much con- 

 troversy has raged. The authors conclude that, while 

 very thin sections can without doubt be best obtained 

 in celloidin, the greater diffirulty of manipulation and 

 the greater requisite dexterity will probably lead an 

 inquirer who wishes to work out a structure quickly 

 and easily to adopt paraffin. As paraffin and celloidin 

 are the chief imbedding agents, each of these is fullv 

 treated in a separat(? chapter, each chapter being of 

 about twenty pages. 



The chapters on stains are particularly full, and 

 every colouring medium appears to be included. The 

 recipes for their composition are given with quantita- 

 tive accuracy, and, in the general preface, Dr. Mayer 

 raises a protest against the vagueness with which such 

 concoctions are frequently quoted. In several cases 

 the important matter of stain durability is suitably 

 discussed. The synonyms of tar dyes are always 

 given. 



It may be that to many investigators the most use- 

 ful chapters will be those which deal specifically with 

 organs and tissues, while other students will perhaps 

 find the chapters on invertebrates the most attractive. 

 Fulness of treatment is as much in evidence in these 

 specialised regions of applied microscopy as in the 

 more general parts of the book. The chapter on em- 

 bryologv (33 pages), for example, covers the animal 

 kingdom ; nerves are treated in three chapters (54 

 pages) ; and, under the heading of Echinoderms, each 

 of the main subgroups is separately described. 



The work as a whole gives the impression of un- 

 varying thoroughness and completeness. It should be 

 a valuable and indispensable auxiliary in the library 

 of everv biological laboratory. An appendix, compiled 

 while the book was in the press, brings the contents 

 thoroughly up to date. A. N. D. 



DARWINISM AND PHILOSOPHY. 

 Dogmatism and Evolution : Studies in Modern 

 Philosophy. By Prof. T. de Laguna and Dr. 

 Grace A. de Laguna. Pp. v + 259. (New York: 

 The Macmillan Co.; London: Macmillan and Co., 

 Ltd., 1910.) Price 75. 6d. net. 



THE authors explain that the term "dogmatism" 

 is here used to denote the body of logical 

 assumptions which were generally made by thinkers 

 of all schools {e.g. Berkeley and Hume, as well as 

 Descartes and Leibniz) before the rise of theories of 

 social and organic evolution. The first part of the 

 work is devoted to the analysis and illustration of the 

 dogmatic principles. The second part, entitled 

 " Revol,ution and Reaction," deals with the opposition 

 offered to the old dogmatism by the critical philo- 

 sophy and absolute .idealism. The third part, which 

 is developed to greater length, deals with the prag- 

 matist revolt. 



From our naturalist's point of view we turn with 

 most interest to what the authors have to say in 

 regard to the Darwinian theory of evolution, and we 

 are not disappointed. It is shown that while the 

 idea of evolution first became effective in the realm 

 «f social science, it was conceived in an essentially 

 NO. 2164, VOL. 86] 



abstract fashion, without any adequate consideration 

 of the factors which operated. "It was not until the 

 work of Darwin in biology that there existed anything 

 like a scientific theor>" of evolution, based on wide 

 and intensive empirical study." But "the import- 

 ance of Darwin's work did not lie simply in the fact 

 that it provided an acceptable theor\' of the evolution 

 of organic species." His success gave investigators 

 in other fields confidence in their clue, and opened 

 the way for a universal theory of evolution. More- 

 over, "the bridging of the gap between man and the 

 lower orders meant a transformation of those sciences 

 dealing with essentially human activities." 



While psychology and ethics have developed in post- 

 Darwinian days under the application of evolutionary 

 methods, logic has until recently remained untouched. 

 " Until the rise of pragmatism no thoroughgoing 

 attempt was made to explain the fundamental notions 

 of logic itself in the light of the selection hypothesis." 

 " Pragmatism is the first whole-hearted attempt at 

 an appreciation of the significance of Darwinism for 

 logical theory." What the authors seek to show i<; 

 that the attempt has only half succeeded ; 



"that conceptions and methods inherited from the 

 dogmatic empiricism of the eighteenth centur}- go far 

 to vitiate the evolutionary empiricism of to-dav; and 

 that the critical revision of these inherited notions 

 from an evolutionary standpoint will make of prag- 

 matism a far less iconoclastic movement." 



The student of organic evolution will be interested 

 in the clear contrast which the authors make between 

 the Darwinian and the Hegelian concepts of evolu- 

 tion. The course of organic evolution is not con- 

 ceived by biologists as a dialectic; it is not to be 

 explained in terms of mere logical relationship; ex- 

 ternal circumstances, instead of being unessential, 

 are determining factors. The later stage cannot be 

 described as the necessary realisation of the earlier. 

 " Had external circumstances been ever so little 

 different, the succeeding stages of the process might 

 have been profoundly different." Organic evolution 

 cannot be properly described as the progressive un- 

 folding of a reality potentially existent throughout. 

 Applying the point of this contrast to rational thought, 

 the authors maintain that on the Darwinian view, 

 thought is regarded not as the end and determinant 

 of organic development, but as a product and (more 

 importantly) as a moment or factor in that develop- 

 ment — "a factor whose existence and nature are 

 throughout conditioned by the part it has to perform 

 in organic life." J. A. T. 



GEOLOGY AND THE DOCTRINE OF 

 DESCENT. 

 Abstammungstheorie mit Riicksicht auf Erdges- 

 chichtc. By Prof. H. Pohlig. Pp. 191. (Stutt- 

 gart : Gesellschaft " Neue Weltanschauung " and 

 F. Lehmann, 1909.) Price 2 marks. 



SCIENCE in England has been peculiarly fortunate 

 in its popular exponents, especially on the bio- 

 logical side ; the onl}- regret is that they are so few. 

 In Germany there is no lack in number, but it would 

 be insincere to express unqualified admiration of the 

 prevailing style. Most of us probably would prefer 



