522 SCIENCE PROGRESS 



The subject-matter of the first three chapters is succinctly stated in their titles 

 thus : I. The Regulation of Breathing; II. The Readjustments of Regulation in 

 Acclimatisation and Disease; and III. Regulation of the Environment, Internal 

 and External. They are very lucidly written and furnish a much-needed account 

 of the phenomena with which they deal. Additional value is added by the fact 

 that they come from one of the pioneer workers who, in addition to possessing a 

 thorough knowledge of his subject, wields an engaging pen. Any one wishing to 

 get a readable account of the research into the mechanism of breathing could not 

 do better than to read these pages, in which the delicate mechanism of adjustment 

 is clearly described. 



In the course of his investigations the author has come to realise a wonderful 

 regulation of the various parts of an animal and an intimate relation between the 

 organism and the environment — a very old mystery encountered by the biologist 

 in almost any field of inquiry. This leads him into a fourth chapter, where we 

 meet such a bewildering welter of Physiology, Philosophy, Metaphysics, and even 

 Theology that it cannot possibly be dealt with in the limits of a short review. In 

 spite of the fact that the author holds both mechanistic and vitalistic interpretations 

 of life to be unsatisfactory, it is the former view that he attacks most strongly, and 

 his own attitude is practically that of a mystic vitalist. He adds little to this old 

 discussion, so far almost profitless, and the arguments he adduces are entirely 

 unconvincing. 



C. H. O'D. 



PALEOBOTANY 



Fossil Plants : a Text- book for Students of Botany and Geology. By 

 A. C. Seward, F.R.S. [Vol. III., Pp. xviii + 656, with 253 text-figures.] 

 (Cambridge : at the University Press, 1917. Price 185-. net.) 



THE scope of this work is monumental, and yet none of the fossils are considered 

 at length : often indeed a page, or half a page, is all that is allowed to important 

 species. Nevertheless, it takes 656 well-filled pages to cover the essential facts 

 concerning but four groups of fossil plants — viz. the Pteridospermeae, Cycadofilices, 

 Cordaitales and Cycadophyta. The science of Palaeobotany is a sturdy infant. 



Seven years have elapsed since the publication of Vol. II. of Prof. Seward's 

 treatise, a time not too long for the preparation of so exacting a work, but one 

 long enough to have rendered it difficult to complete, because almost every month 

 has seen some addition to knowledge concerning these particular groups of fossils 

 which have been the frequent subject both of original inquiry and explanatory 

 controversy. That such a work should have been completed at all is a cause of 

 congratulation, and university students and research workers must be grateful 

 for a valuable reference-book. It is, however, hardly a book to be read through 

 from cover to cover, save perhaps by an eager youth cramming for an examina- 

 tion, though the immense mass of data packed within its pages can surely never 

 be retained by any one brain. 



The four groups dealt with afford a rich harvest of interest. On the one hand, 

 they cover representatives of families entirely extinct, though linked remotely with 

 the primitive living Gymnosperms, revealing an immense variety of detail among 

 those early seed plants, many of which had so much the external appearance of 

 still extant ferns. On the other hand, the chief mesozoic representatives of the 

 Cycadophyta, conversely, are peculiarly interesting as having had, with the 

 external appearance of still extant cycads, so much more complex fructifications 

 than any living member of the group. 



