June 7, 1900] 



NA TURE 



125 



I 



The author gives in tabular form an estimate of the 

 population, coal output, export and consumption for the 

 years 1899 to 1950, by which date the 15,000 million tons 

 assumed to be now remaining will be exhausted. The 

 prosperity assured by the coal of the country to naviga- 

 tion, manufactures and commerce will then gradually 

 disappear, and the historian of a powerful empire will 

 conclude, the author prophesies, his account of a remark- 

 able period by the words : Finis Britanniae ! Happily, 

 however, the array of statistics, the copious particulars 

 of the coal-seams, and the faithfully translated estimates 

 of eminent experts do not altogether justify the author's 

 Cassandra-like attitude. 



The work has been compiled with great care, and the 

 author deserves high praise for the accuracy with which 

 the names of English places and persons have been 

 presented. On p. 564 there is a curious slip. Speaking 

 of the introduction of railways in 1844, the author says : 

 " Mme, aubergiste of the George^ pleurait la fin des 

 diligences." The archaic expression "Mine host" has 

 proved too severe a test for the author's undoubtedly 

 extensive knowledge of the English language. 



Bennett H. Brough. 



OUR BOOK SHELF. 

 Ueber den Bau und die Entwicklung der Linse. By 



Dr. Carl Rabl. Pp. 324 ; plates 14. (Leipzig, 1900.) 

 In the " Notes" column brief mention has recently been 

 made of the concluding portion of Dr. Rabl's important 

 investigations on the structure and development of the 

 crystalline lens of the eye, which appeared in the 

 Zeiiscrhift fur wiss. Zoologie. The author has now 

 reproduced the entire monograph as a separate work, 

 with the original coloured plates ; and since it is a most 

 elaborate treatise on a very difficult subject, its appear- 

 ance in this form should be welcomed by all students of 

 this branch of anatomy. 



There are, perhaps, few phenomena in the develop- 

 mental history of animals more astounding to the 

 ordinary mind than the fact that a structure seated so 

 comparatively deep as is the crystalline lens of the 

 human eye should arise from the outer, or epiblastic, 

 layer of the embryo, and attain its permanent position, 

 first by invagination, and then by separation from its 

 parent layer. Nevertheless, it is a fact about which 

 there can be no possibility of dispute ; and the more 

 superficial position occupied by the spherical lens of 

 fishes serves, in a measure, to indicate the manner in 

 which the conditions obtaining in the mammalian eye 

 have been gradually evolved. 



By means of the beautiful series of plates illustrating 

 Dr. Rabl's work the student is enabled to comprehend 

 at a glance, firstly, the mode of development of the lens 

 respectively characteristic of fishes, amphibians, reptiles, 

 birds and mammals ; and, secondly, the different histo- 

 logical peculiarities presented by the lens itself in the 

 same groups. Within the limits of a notice in this 

 column, it is out of the question to discuss any details of 

 the work before us ; but it may be mentioned that in the 

 concluding section the author enters into the abstruse 

 speculation as to what may have been the degree of de- 

 velopment of the eye in Archaeopteryx and other extinct 

 animals, and also as to the gradations which may have 

 formerly existed between the present differentiated types 

 of lens-structure. Very interesting, too, are his ob- 

 servations with regard to the lens in the aborted eye 

 of the mole. Here the rudimentary condition of the 

 lens does not commence in the course of development, 

 or in the fully adult animal ; but it is distinctly ob- 



^O I597> VOL. 62] 



servable in the earliest stages, when it is relatively- 

 smaller and contains fewer cells than in other mammals. 

 Hence we have evidence of the extreme antiquity of the 

 mole's adaptation to its present state of existence — 

 evidence fully supported by paheontological facts. 



The work may be characterised as a masterpiece of 

 patient and careful investigation in an abstruse and 

 difficult line of research. R. L. 



Building Construction for Beginners. By J. W. Riley. 



Pp. vi -I- 255. (London : Macmillanand Co., Ltd., 1899.) 

 Thls is an addition to the increasing number of works 

 on Elementary Building Construction, which all have for 

 their ultimate goal the preparation of students ior the 

 May examinations of the Department of Science and Art. 



Commencing with the inevitable introductory remarks 

 on drawing instruments and scales, the student is taken 

 through all the various building trades, and at the end of 

 each are added questions in the form of examination 

 papers which should test the student's knowledge as he 

 advances. 



As the author observes, isometric projection is a very 

 valuable means of showing the beginner exactly what is 

 intended, as it gives in one view the plan, elevation and 

 section of the object portrayed. We are glad to see 

 that an extensive use is made of such a form of 

 illustration. 



We may also congratulate our author on abstaining 

 from confusing his illustrations by figuring with too 

 many dimensions. Some authors refer with pride to their 

 use of such a system, but as Mr. Riley observes, it is very 

 confusing, and tends by its complication to hinder the very- 

 object for which it is introduced. 



In a new edition several small slips can be attended to,, 

 such, for instance, as ithe wall-plate surroundings in 

 Fig. 384. The brickwork in this case should be taken up- 

 to the underside of the tiles. The " summary " at the 

 end of each trade is an excellent innovation, and the 

 book can be confidently recommended as the best of its 

 class. 

 Catalogue of the Fossil Bryozoa in the Department of 



Geology, British Museum {Natural History). The 



Cretaceous Bryozoa. Vol. i. By Dr. J. W. Gregory. 



Pp. xiv -f- 457, and plates. (London : Printed by the 



order of the Trustees, 1899.) 

 We may congratulate Dr. J. W. Gregory in having com- 

 pleted this volume before he left this country to take up 

 the geological professorship at Melbourne. The value 

 of this, and similar works, is inestimable to palaeonto- 

 logists in all parts of the world. The book itself is 

 naturally a list of hard names ; but it is something now- 

 adays to know which is the correct name to apply to 

 any particular fossil, and Dr. Gregory gives as far as 

 possible the synonymy, diagnosis, dimensions and geo- 

 logical distribution of each species. A number of wood- 

 cuts in the text and seventeen excellent plates illustrate 

 a great many of the species. We should have been 

 glad of a table of the Cretaceous strata, to inform or 

 remind us of the approximate British equivalents of such 

 divisions as Rhodanian, Campanian, Hauterivian, &c., 

 and also to indicate the sense in which the terms Neo- 

 comian and Cenomanian are used. 



The volume deals with the various families which are 

 included under the sub-orders Tubulata, Cancellata and 

 Dactylethrata. All these are ranged under the order 

 Cyclostomata, the sub-class Gymnolasmata, the class 

 Ectoprocta and the group Bryozoa. It will be remem- 

 bered that in the catalogue of recent marine forms 

 in the British Museum, by Busk, that author employed 

 the term Polyzoa instead of Bryozoa. The effort to 

 secure a fixity in zoological nomenclature is one of the 

 trials which beset the path of the worker. Dr. Gregory's 

 carefully prepared catalogue will, we hope, have a per- 

 manent value in this respect. 



