DISCOVERY 



77 



them. Much depends also upon social environment. 

 Among the Romans the existence of large resources of 

 slave labour discouraged the exercise of ingenuity. 

 What stimulus was there toward inventing means of 

 rapid reproduction of documents when slave cop\'ists 

 were at hand ? .\ccount must also be taken of the 

 fact, noted by the late Professor Bain in his Mental 

 and Moral Science, that as a rule it is only in modern 

 times that the perception of similarities has been a 

 force making for invention, as in the case of the 

 " governor halls " of Watt. .And, of course, we must 

 ne\-er forget what mechanical progress owes to the 

 enunciation of Bacon's great maxim that we cannot 

 conquer Nature save by obeying her laws. 



Reviews of Books 



A Textbook of Plant Biology. By W. Neilson Jones 

 .\ND M. C. R.^YNER. (Methuen & Co., 7s.) 



An Introduction to the Structure and Reproduction of 

 Plants. By F. E. Fritch and E. J. Salisbury. 

 (G. Bell & Sons, 15s.) 



There has recently been a fairly general tendency on 

 the part of botanists to modify their methods of teaching ; 

 for many years the practice was to illustrate the characters 

 of the various groups of plants by the description and 

 examination of seleeted types, to pay comparatively little 

 attention to the chemistry and physics of the living 

 organism, and to emphasise form and structure rather 

 than the methods by which plants live and react to their 

 environment. The enormous advance in recent years in 

 our knowledge of Biochemistry, fhat is the chemistry- of 

 Uving things, has demonstrated the importance of intro- 

 ducing the student at an early stage to the conception 

 of plants as working machines requiring energy, and 

 depending for their efficiency upon chemical reactions 

 in the living cells. The more old-fashioned methods of 

 presenting the subject did not sufficiently recognise the 

 unity of life. It is still difficult for many people to grasp 

 the fact that plants are just as much alive as animals, 

 and that the two kingdoms represent divergent lines of 

 evolution from common ancestors which were neither 

 plants nor animals as these are generally understood. 



The book on Plant Biology by Professor Jones and Dr. 

 Rayncr is divided into three parts: The plant as a 

 machine ; the plant in relation to the outside world ; 

 reproduction. Throughout the volume there are directions 

 for simple and well-chosen experiments.- A student who 

 has mastered the course of study proposed cannot fail 

 to realise the nature of the problems with which a plant 

 is confronted and the means by which the problems 

 are solved. As the authors point out, their book does 

 not profess to be a general treatise ; it introduces the 

 reader to the fundamental principles of Biology, and 



encourages him to see things for himself and to take as 

 little as possible on trust. 



The volume by Professor Fritch and Dr. Salisbury is 

 a sequel to their Introduction to the Study of Plants, and 

 while complete in itself, within the limits suggested by the 

 title, it is primarily a te.vtbook for students who wish to 

 carry the study of plants beyond the stage at which a 

 knowledge of minute structure and details of life-histories 

 was not demanded. The authors state that they have 

 " abandoned the study of isolated types in favour of a 

 more general account, indicating the range of form-and re- 

 proiluctive methods within each group." They have also 

 endeavoured " to combat the frequent ignorance of 

 botanical students with respect to the ecomonic aspects 

 of their subject." The book is clearly written and on 

 the whole well illustrated ; the comparative method 

 of treatment is an attractive feature to which greater 

 prominence is given than in many textbooks. The 

 physiological side is not neglected, and as far as possible 

 structure and function are considered together. 



These two volumes may be recommended with confi- 

 dence as trustworthy guides to the modern method of 

 studying botany, and the latter volume forms a suitable 

 companion to that on Plant Biology. In both the subject 

 is made attractive by a breadth of view and by emphasis 

 on physiology. Elementary students with some know- 

 ledge of chemistry and physics can easily follow both 

 pairs of authors ; advanced students will learn a good 

 deal, and the teacher will find many useful hints for 

 practical exercises and methods of presentation. 



.\. C. Seward. 



Devonian Floras : a Study of the Origin of Cormophyla. 

 By E. A. Newell Arber, with a Preface by 

 Dr. D. H. Scott. (Cambridge University Press, 

 17s.) 



This book was prepared for tlie press by Mrs. Arber 

 from a first draft written by Dr. .Vrber shortly before 

 his death in 191 8. Dr. Scott, in the Preface, gives a brief 

 summary of the several chapters, and writes sympatheti- 

 cally of the " bold and vigorous effort " made by the 

 author to grapple with the problems of evolution presented 

 by the oldest known land-plants. Dr. Newell Arber, 

 of whom an excellent photograph is reproduced as a 

 frontispiece, was one of the most devoted workers in 

 the attractive field of pateobotany ; his researches added 

 very considerably to our knowledge of fossil plants of 

 tlifferent ages, and his more general papers dealing with 

 questions of theoretical interest were both able and 

 stimulating. In this his last work he gives an admirable 

 summary of the salient features of Devonian plants 

 described from many parts of the world, and discusses, 

 with much independence of thought and originality, the 

 bearing of the botanical data upon the evolution of the 

 earliest land-plants. The theory advanced in the latter 

 part of the book, which had not been revised by the 

 author, of the origirr of the Cormophyta — that is, plants 

 exhibiting a differentiation into definite organs performing 

 different functions — raises many controversial questions ; 



