198 



NATURE 



[April 14, 192 1 



groups, but he adds that these characters "may, 

 after all, admit of a different explanation." It 

 may be that he has less faith in common an- 

 cestors than he once had, and if this surmise be 

 true he is not alone in this sceptical attitude. Dr. 

 A. H. Church believes that ferns and lycopods 

 represent separate lines of evolution from uni- 

 cellular flagellates, and, as Dr. Scott remarks, 

 it would be rash to reject Dr. Church's hypo- 

 thesis of transmigration simply on the ground of 

 the synthetic nature of such a plant as Astero- 

 xylon. 



Few additions have been made to the earlier 

 chapters of the volume. To that on Sigillaria 

 and allied genera an account has been added of 

 a remarkable heterosporous lycopodiaceous cone 

 from the Coal Measures, the genus Mazocarpon, 

 described by Dr. Margaret Benson. The section 

 devoted to the ferns, which has been in part re- 

 written, is a particularly welcome contribution to 

 a puzzling subject. It is now recognised that 

 the ferns did not hold the dominant position in 

 the Palaeozoic period formerly assigned to them ; 

 there were tree ferns and simpler herbaceous 

 genera exhibiting a wide range in their morpho- 

 logical characters, in some features strikingly 

 similar to modern forms, in others very different. 

 Their origin is an unsolved problem. The ad- 

 mirable work of Dr. Kidston and the late Prof. 

 Gwynne-Vaughan on the fossil Osmundaceae is 

 briefly summarised, and the recent researches of 

 Dr. Gordon, M. Paul Bertrand, and others on the 

 Botryopteridaceae are described and correlated 

 with conspicuous success. 



In the last chapter Dr. Scott gives a very good 

 account of the already famous genera Rhynia, 

 Hornea, and Asteroxylon, founded on exception- 

 ally well preserved material from a bed of Middle, 

 or possibly Lower, Devonian chert discovered in 

 1913 by Dr. Mackie, and thoroughly investigated 

 by Dr. Kidston and Prof. Lang. These plants, 

 admirably described and illustrated in Prof. 

 Bower's lectures, published in Nature for July 29 

 and August 5, 1920, afford us glimpses of what, 

 so far as we know at present, is the oldest land 

 vegetation ; though separated by an interval of 

 several hundred millions of years from existing 

 plants, they exhibit anatomical characters won- 

 derfully similar to those of certain recent types. 

 In some respects these Devonian genera are more 

 primitive than any living Pteridophytes, and, like 

 so many extinct plants, they appear to have attri- 

 butes of phyla that are now widely separated. 

 What was their history? Do they bring us 

 within sight of the transition from algae to vas- 

 cular plants suggested by Dr. Arber (in a 

 NO. 2685, VOL. 107] 



posthumous book,i to which Dr. Scott refers), 

 and advocated with much ability and in- 

 genuity by Dr. Church in a recent memoir? 

 Whatever the significance of the older Devonian 

 plants may be, botanists have now an opportunity 

 of reading an excellent account of the facts. 



It is superfluous to commend Dr. Scott's book 

 to botanists familiar with the earlier editions, but 

 one may express the hope that this up-to-date 

 survey of the field selected for treatment, pre- 

 sented in a form which reflects the greatest 

 credit upon author and publisher, may lead many 

 botanical students to appreciate at their true value 

 the older records of the rocks, and to endeavour 

 to form an unbiassed opinion on the bearing of 

 palaeobotanical evidence on the general question of 

 the method by which the plant world has been 

 evolved. As Prof. Bateson says, "we have got 

 to recognise that there has been an evolution. "^ 

 Is it true, as we are often assured, that the 

 study of fossil plants confirms the orthodox views 

 on progressive development, or do the results of 

 modern research into the floras of the past compel 

 us to admit greater ignorance of the course of 

 plant evolution than is generally allowed? The 

 great value of the volume under consideration is 

 that it gives us a well-proportioned statement of 

 the more trustworthy results of palaeobotanical 

 inquiry, and provides the student with the means 

 of forming his own conclusions. 



A. C. Seward. 



A Modern Inorganic Chemistry. 



A Text-book of Inorganic Chemistry for Uni- 

 versity Students. By Prof. J. R. Partington. 

 Pp. xii-l-1062. (London: Macmillan and Co., 

 Ltd., 1921.) 255. 



THE general arrangement of this book is 

 logically worked out on a well-ordered 

 plan, and the author has a straightforward and 

 easy style. The result is a very readable volume, 

 which is, in our opinion, the best of its kind in the 

 language. 



The introductory chapters are excellent, as also 

 are those sections dealing with the development 

 of fundamental chemical theories during the nine- 

 teenth century. In fact, the historical aspects of 

 the subject are well emphasised throughout. (W^e 

 must, however, dissent from the desirability 

 of referring atomic weights to the standard H = i. 

 The difficulties from the point of view of the 

 student caused by the use of- the oxygen standard 



1 This volume, entitled " Devonian Floras," was published in January 

 last. 



