238 



NATURE 



[April 20, 191 1 



engineering section of the ••Encyclopaedia." although 

 there is no clear indication of the principle on which 

 the subjects have born stltctcd. The biography of 

 Sir Henjamin Baker is hardly worthy of the man. 

 'JTie article is very brief, and it gives no adequate idea 

 of the great engineering w^rks for which liaker was 

 responsible. This is much to be regretted. On the 

 other hand, the notices of Hessemer and Brassey 

 (father of Lord Brassey) contain excellent summaries 

 of widely differing careers. The description of the 

 •• swinging saloon ** devised by Bessemer for cross- 

 Channel steamers, and of the failure of that system 

 in practice, illustrate the danj^ers attaching to ven- 

 tures into new regions even when they are made by 

 capable inventors who have achieved success in other 

 directions. Bessemer had pot mastered the prin- 

 ciples of the behaviour of ships at sea, otherwise he 

 would not have attempted to keep a swinging saloon 

 level as the steamer rolled by the control of an 

 attendant who watched the indications of a spirit-level, 

 and manipulated hydraulic machinery. Thomas 

 Brassey was not an engineer, but was simply one of 

 the first and g^reatest contractors for engineering 

 works. He is shown to have been a man of great 

 business and administrative capacity. The sketch 

 of his life brings into relief his high personal quali- 

 ties and illustrates the fact that he "was one of the 

 first to aim at improving the relations between 

 engineers and contractors, by setting himself against 

 the corrupt practices which were then common." 



W. H. W. 



EXPERIMENTAL ZOOLOGY. 

 Expcriincntal-Zoologie. 3 : Phylogenese. By Dr. 

 H. Przibram. Pp. viii + 315 + xxiv. plates. (Leip- 

 zig und Wien : F. Deuticke, 1910.) Price 18 

 marks. 



THIS volume, the third instalment of the author's 

 work on experimental zoology, is planned on the 

 same lines as the preceding parts; it deals essentially 

 with the nature of species and the origin and modifica- 

 tion of specific characters. It gives a concise sum- 

 mary of the work which has been done in various 

 branches of the subject, with short discussions and 

 criticisms where the author considers them necessary. 

 It is on the whole, however, rather an encyclopaedia 

 of the phenomena of species than a discussion, as is 

 indicated by the fact that 70 out of 315 pages are 

 devoted to the bibliography and index. In some cases 

 rather more criticism would have been welcome, for 

 the author summarises papers of very different im- 

 portance with an impartiality which sometimes makes 

 it difficult to gauge the relative value of the work. 



In general, the treatment is exceedingly complete, 

 and includes accounts of papers which might have 

 been overlooked without giving just cause for com- 

 plaint, but there are a few rather surprising omis- 

 sions. For example, in dealing with heredity, the 

 work of the biomctrician school is scarcely mentioned 

 apart from Galton's formulation of the law of ances- 

 tral inheritance; Nettleship's Bowman lecture on 

 hereditary eye-diseases is omitted; and still more sur- 

 prising is the absence of tmy reference to Gamble and 

 2^0, 2164, VOL. 86] 



Keeblc's work on the effects of coloured surrounding;* 

 on pigment development. Poulton's work on tli'r 

 same subject is also treated rather inadequate!) 



The plates are of the semi-diagrammatic kind u^cv. , 

 the first volume, and are excellent as illustrations t : 

 the text; they are folded so that a plate can be turn»<l 

 out for reference while reading, but it would make it 

 easier to find the plate required if the numbers wer. 

 visible when they are folded. As in the previou- 

 volumes, the use of the letters a and a is soni« 

 confusing; in plate vii. we notice that the nur. •: 

 4a and 4c are interchanged, and in the description of 

 plate xxiv., Fig. 14, the use of the word " hetero- 

 zygote " is misleading. We mention these small 

 defects in the hope that an English translation will 

 be undertaken, in which they may be remedied. 



The book opens with a discussion of the criteria 

 of species, in which the importance of physiological 

 characters (blood tests, &c.) is emphasised, and a 

 tabular summary is given of various classes of specitic 

 characters. The two short chapters which follow 

 deal with the possibilities of asexual (somatic) and 

 sexual transmission of characters. Chapter iv. con- 

 sists of a very complete catalogue of experiments in 

 hybridisation, both of crosses between distinct species, 

 and between races or varieties. This fills 100 pages, 

 and is most valuable as a list of all the most importiint 

 cases up to the year 1909. In the succeeding chapttr 

 these results are analysed. It is concluded that the 

 first cross (FJ may show (i) a blend, (2) a mosaic, or 

 (3) alternative appearance of the parental characters. 

 In the F3 generation the first and second classes may 

 give young all like F,, or Mendelian segregation may 

 occur; the third class always gives a Mendelian 

 result. The view that Mendelian characters are 

 borne by chromosomes is provisionally accepted. A 

 good account is given of dihybrid and polyhybrid 

 cases, and of the phenomena of "latency" and sex- 

 limited inheritance. In crosses between distinct 

 species the characters often blend, because apparently 

 corresponding characters in different species are not 

 allelomorphic. The relation of Mendel's and GaUon's 

 laws to each other is described, and in a discussion 

 of the relation of alternative to blended inheritance a 

 suggestion is made for bringing both into one 

 category. 



Chapter vi. (63 pages) gives a summary of work in 

 the production of characters by environment, and 

 their inheritance. Among the work on Protozoa, 

 Dallinger's experiments are not mentioned; and in 

 the long section devoted to the Lepidoptera, we think 

 that a fuller discussion might have been given of the 

 means by which colour-production is influenced by 

 temperature and other factors, as indicated, f or • 

 example, by Griifin von Linden's work. The 

 theoretical conclusions to be drawn from this chapter 

 are postponed to the end of the book. In the chapters 

 on selection and mimicry, a good account is given of 

 experiments and observations by various workers, and 

 it is concluded that although natural selection can 

 bring about the survival of the fittest, and although 

 mimicry of a noxious species may be a protection to 

 the mimic, yet selection can originate nothing, but 

 only isolate "pure lines" already existing. 



