226 



NATURE 



[October 28, 1915 



are not surprised to find no reference to the 

 "thinking horses" of Elberfeld. There are effec- 

 tive illustrations, and the printing of both books 

 is such as suits both young and old eyes. 



(3) Mr. Dixon has the courage of his anthropo- 

 morphism, which is of the deepest dye. For he 

 maintains that plants " see, hear, taste, feel, walk, 

 swim, run, fly, jump, skip, hop, roll, tumble, set 

 traps, and catch fish ; decorate themselves that 

 they may attract attention ; powder their faces ; 

 imitate birds, animals, serpents, stones; play 

 hide and seek ; blossom underground ; protect their 

 children, and send them forth into the world pre- 

 pared to care for themselves — indeed, do all those 

 things which we ourselves do. We now know 

 that plants have even minds and souls, with which 

 to think and to worship." 



This is partly a rebound from a horttis siccus 

 botany, partly an uncritical vitalism, and partly a 

 somewhat saddening illustration of the lack of 

 critical balance. Saddening, we call it, because 

 the author has a fine series of most interesting 

 facts to set forth concerning the intense vitality 

 of plants, their movements, their sensitiveness, 

 their adaptations, and their purposiveness (we do 

 not say purposefulness), and yet he has gone and 

 queered his pitch with an intolerably anthropo- 

 morphic and sentimental phrasing. 



No one can be very enthusiastic over the botan- 

 ist's terminology of chemotaxis, heliotropism, 

 nyctinastic movements, and the like, but there 

 should be some middle way between this and talk- 

 ing, as Mr. Dixon does, about the activities of 

 plants as if they were on a plane with our own. 

 We do not blame the author for regarding plants 

 as psycho-physical beings — which seems to us a 

 position which can offer a strong defence — nor 

 even for speaking, if he wishes, about their senses 

 (seven in number) and experiments, their "men- 

 tality and spirituality " ; we blame him for lead- 

 ing the unwary to think that plants tackle the 

 business of life on anything like human lines. 

 For this will have to be unlearnt. Theirs is cer- 

 tainly another way, even farther from our under- 

 standing than instinct is. 



TEXT-BOOKS OF PHYSICS. 

 (i) Elements of Optics for the Use of Schools and 

 Colleges. By G. W. Parker. Pp. iv+122. 

 (London : Longmans, Green and Co., 1915-) 

 Price 2s. 6d. 



(2) Elementary Experimental Statics. By L B. 

 Hart. Pp. vii + 200. (London and Toronto : 

 J. M. Dent and Sons, Ltd., 191 5.) Price 2S. 6d. 



(3) Introduction to Heat. By A. R. Laws and 



NO. 2400, VOL. 96] 



P.W.Todd. Pp. X -1-2 12. (London : Mills and 



Boon, Ltd., 1915.) Price 2s. 6d. 

 (4) Experimental Harmonic Motion: a Manual for 



the Laboratory. By Dr. F. G. C. Searle. Pp. 



x + 92. (Cambridge: At the University Press, 



1915.) Price 45. 6d. net. 

 (i) TN Mr. Parker's "Elements of Optics" the 

 1 subjects of reflection, refraction, mirrors 

 and lenses, simple optical instruments, and dis- 

 persion are dealt with in four chapters. The book 

 is intended for beginners", and no further mathe- 

 matical knowledge is required for its perusal than 

 an acquaintance with elementary geometry, simple 

 algebraic equations, and the trigonometrical 

 ratios. The text consists chiefly in the derivation 

 of the usual formulae of geometrical optics, the 

 deviation method being employed for mirrors and 

 lenses. The statements are accurate and concise, 

 and the diagrams clear. Many teachers will 

 regard the book as being too sparse and some- 

 what uninteresting owing to the absence of ex- 

 perimental matter. The inclusion of experiments 

 to verify the laws and results by the aid of simple 

 and inexpensive apparatus, wOuld have enhanced 

 the value of the book considerably. Numerical 

 exercises are interspersed in the text, and answers 

 are supplied. 



(2) " Elementary Experimental Statics," by Mr. 

 Ivor B. Hart, is written for pupils beginning the 

 subject of mechanics. The mathematical know- 

 ledge assumed does not extend beyond an ac- 

 quaintance with simple algebraic equations. The 

 author deals with parallel forces, centres of 

 gravity, inclined forces, friction, and the simple 

 machines. The chief elementary facts are im- 

 pressed on the pupil by a series of simple experi- 

 ments. Full directions for the performance of 

 these experiments are given, and the method of 

 recording the results is indicated. It is better to 

 insist on the tabulation of actual observations 

 than results obtained after a mental calculation, 

 as in col. 5 of the table on p. 45. The book is 

 provided with a large number of questions and 

 numerical exercises. The pupil who performs the 

 experiments and works the examples in this book 

 will have laid a good foundation for further study 

 in experimental science. 



(3) "Introduction to Heat," by Messrs. Law^s 

 and Todd, may be used both as a class and labora- 

 tory text-book in schools. The aim of the authors 

 has been to introduce many phenomena from 

 everyday life, and by appealing to the ordinary 

 experiences of the pupil to awaken an intelligent 

 interest in the subject. The order of treatment is 

 somewhat different from that usually adopted in 

 text-books of this character. The opening chapter 



