166 SCIENCE PROGRESS 



Comparing the first volume, with which we are here concerned, with the single 

 volume of the first edition, we find that its 363 pages and 128 illustrations contrast 

 favourably with the 533 pages and 151 illustrations of the latter. The rise in price 

 (an increase of three shillings where the two volumes are bound together, or of three 

 and six when they are purchased separately), is happily not in proportion, and no 

 one is likely to grudge the extra cost. 



Yet while there is much that is new to the old edition, the scope and purpose 

 of the work remain unchanged. The author's object is still to present "those 

 results of pal?eontological inquiry which appear to be of fundamental importance 

 from the botanist's point of view." His attitude on the whole has been very 

 conservative as to the treatment and arrangement, and the present volume is in the 

 main the former edition revised and brought up to date, so far as its limits extend. 

 These limits include the Pteridophyta, the Spermophyta being reserved for the 

 second volume. 



Some chapters have naturally required more extension and revision than 

 others, and this is particularly the case with those devoted to the Ferns. The 

 whole subject of the palaeozoic ferns has had to be considered afresh in the light 

 of the discoveries of the last few years. The account given in the present volume 

 is the most complete we possess, and contains a description of some new and 

 interesting members of the group. 



As to the general excellence of the text it is unnecessary to speak. A word of 

 praise may, however, be added in regard to the illustrations, which with few 

 exceptions are adequate, and in all cases clear. 



We notice one inconsistency, for which the author is no doubt not responsible. 

 The book is called Volume I. on the title-page and in the preface, whereas on the 

 cover it is labelled Part I. Certain sections, such as the descriptions of Bothro- 

 dendron and Archceocalamites, do not appear to be treated so fully as the rest, and 

 might with advantage have been rather more expanded. But the author, no 

 doubt in view of the space available, has perhaps wisely reserved for consideration 

 at greater length those subjects which he has deemed the more important. 



The literature, especially the more recent memoirs, is quoted, though not perhaps 

 quite so fully as one could wish. It would be of great service to students, and 

 also render this department more complete, if at the end of the second volume a 

 bibliography of all the more important papers on structure-material were included. 



E. A. Newell Arber. 



Introduction to Metallography. By Paul Goerens, Dr. Ing. Translated 

 by Fred. Ibbotson, B.Sc. (London ; Longmans, Green & Co. ; price 

 "js. 6d. net.) 



THIS book is particularly useful for those who either intend to study metal- 

 lography or who are actually engaged in work of this nature but are not 

 acquainted with the fundamental principles underlying the science. In order to 

 understand the structure of metals revealed under the microscope, it is generally 

 essential to have a thorough knowledge of the critical changes that occur during 

 their solidification and subsequent heat treatment. In Dr. Goerens' book, this 

 branch of physical metallurgy is treated in a particularly lucid and interesting 

 manner, and the reader is in no way troubled with the irrelevant matter frequently 

 found in works on this subject. Only those portions of physical metallurgy 

 necessary for metallographical purposes are given which would enable a beginner 

 to obtain a knowledge of the methods of investigating metals and alloys. 



