September 8, 192 1] 



NATURE 



39 



Our Bookshelf. 



Catalogue of the Fossil Bryozoa {Polyzoa) in 

 the Department of Geology, British Museum 

 {Natural History]. The Cretaceous Bryozoa 

 {Polyzoa). \ol. 3. The Cribrimorphs. — Part 

 I. By Dr. W. D. Lang. Pp. 12 + ex + 269 + 

 8 plates. (London : British Museum (Natural 

 History), 1921.) 305. 

 Though the price must at present remain high, 

 the issue of this volume is, we hope, a sign that 

 research in our public scientific institutions will 

 still find means of publication. Museums and 

 geological surveys flourish largely by interchange 

 of ideas, and the volumes issued by smaller coun- 

 tries — Finland is now a notable example,* and 

 Poland has come into the field — may react on 

 those who would restrict the official output of 

 Britain to works of economic value. Dr. Lang 

 here presents us with, careful descriptions of co- 

 ordinated fossil species; but his biological intro- 

 duction shows how he bears in mind their history 

 as living things. He finds no obvious utility in 

 the mode in which bryozoa have deposited cal- 

 cium carbonate in a variety of artistic forms, and 

 he regards such deposition, even in molluscs, as a 

 mode of getting rid of material not required by 

 the living tissue. He admits a protective result 

 in many cases, but not a protective intensification 

 through natural selection. In bryozoa the details 

 of skeletal structure seem to him " due to the 

 necessity of piling up superfluous calcium car- 

 bonate where it least interferes with the 

 organism's bionomy." We are glad to note 

 that this work is produced on good paper in har- 

 mony with its many predecessors. 



G. A. J. C. 



Critical Microscopy : How to Get the Best out of 

 the Microscope. By Dr. A. C. Coles. Pp. 

 viii-h ioo-f3 plates. (London: J. and A. 

 Churchill, 192 1.) 75. 6d. net. 

 Dr. Coles gives a clear account of various small 

 alterations in his microscopical outfit which have 

 enabled him to obtain better results, and he 

 describes concisely the methods and adjustments 

 necessary in order to obtain the highest resolv- 

 ing power. He has had particularly in mind the 

 needs of protozoologists who have often to search 

 for a minute organism present in small numbers. 

 For conducting such a search the author strongly 

 advises the use of a dry lens, such as the 8-mm. 

 apochromatic, which can be employed on covered 

 or uncovered preparations and with ordinary 

 transmitted light, or with dark-ground illumina- 

 tion. He gives details of his method, first pub- 

 lished in 1914, for detecting the presence of 

 spirochaetes, in uncovered preparations, with this 

 low magnification. His account will be helpful 

 to many workers who may not have realised how 

 much can be done with a good 8-mm. objective. 

 L'seful hints are also given on sub-stage con- 

 densers, dark-ground illumination, and photo- 

 micrography. The author directs attention to the 



NO. 2706, VOL. I08I 



great importance of applying a correction for the 

 thickness of the cover glass by means of a cor- 

 rection-collar on the objective, or, better, by altera- 

 tion in the tube length. He quotes a number of 

 useful explanations, by Mr. E. 'SI. Nelson, of the 

 optics of the microscope. A short explanatory 

 note on "numerical aperture" and its signifi- 

 cance might have been added. 



Stanford University Publications , University 

 Series: Mathematics and Astronomy. Vol. i. 

 No. I : Primitive Groups. Part i. By Prof, 

 W. A. Manning. Pp. 108. (California : Stan- 

 ford University, 1921.) 1.25 dollars. 

 The first eighty pages of this book are devoted 

 to an introduction to the theory of finite groups 

 somewhat on the lines followed by many similar 

 treatises. A special feature is the early stage at 

 which group-characteristics are discussed, and 

 nearly half of the introductory portion of the book 

 is given up to an investigation of their properties 

 and applications. The author makes no very 

 marked distinction between permutation-groups, 

 substitution-groups, and abstract groups, but 

 passes easily from one to the other, as suits his 

 purpose. His style is pleasant, but the proofs 

 are a trifle condensed, as if he had felt acutely 

 his limitations of space. The book will be more 

 useful to the reader who has some slight acquaint- 

 ance with the subject than to the beginner. 



The properties of primitive groups occupy the 

 last third of the treatise, which is far more 

 specialised and contains more original matter. 

 These pages will appeal to the intending re- 

 searcher rather than to the mathematician requir- 

 ing a knowledge of general outlines. 



Print and arrangement are quite attractive. 

 There is a good contents list, but the absence of 

 an index is regrettable. If the remaining Stan- 

 ford University publications all come up to the 

 standard of this first number, they will indeed 

 fulfil a useful purpose. Harold Hiltox. 



Moby-Dick or the Whale. By H. Melville. With 

 an introduction by Viola Meynell. (The 

 World's Classics.) Pp. xii-f675. (London: 

 Humphrey Milford : Oxford University Press, 

 1920.) 2s. 6d. net. 

 This highly dramatic story, first published in 

 1 85 1, though but little known to present-day 

 readers, is a remarkable literary achievement, and 

 deserving of attention on that score. In the 

 course of its thrilling chapters is one entitled 

 "Cetology," in which is given a whaler's descrip- 

 tions of all the known species of Cetacea, their 

 habits, distinctive features, and commercial value. 

 The descriptions are embellished with many 

 literary flourishes, but are nevertheless vivid and 

 have a certain zoological value. "Mobv-Dick" is 

 a white sperm-whale that is madly pursued by one 

 Ahab, who in the past has suffered loss bv its 

 jaws. More of the tale we must not tell : suflfice 

 it to say that " Midshipman Easy " and " The 

 Cruise of the Cachalot " pale beside it. 



