692 SCIENCE PROGRESS 



contrast the seed of P. Sabiniana is from 18-22 mm. in length, and the seedling 

 possesses from 12-17 cotyledons, which attain a length of from 50-55 mm. 



The second part concludes with a clavis to the genera of epigeal Dicoty- 

 ledonous seedlings, which, it may be noted, outnumber the hypogeal by about 

 4 to 1. 



To the botanist and to the professional forester alike, these volumes 

 should prove of considerable value, both from their practical utility and 

 their theoretical importance. 



E. J. Salisbury. 



Joseph Dalton Hooker. By Prof. F. O. Bower, Sc.D., F.R.S. [Pp. 62, 

 with frontispiece.] (London : Society for Promoting Christian Know- 

 ledge, 1919. Price 25. net.) 



It is but fitting that a life of Sir J. D. Hooker should find its place in the 

 series of volumes dealing with pioneers of progress. But to do justice to his 

 many activities during so long a period of years is no light task. 



The author has, however, in these eight chapters, by devoting each to a 

 different view-point, attained a considerable measure of success. 



The chapters entitled " Kew " and " Authorship " serve to present Sir 

 Joseph's administrative achievements and his chief contributions to science 

 But in reference to the former, one regrets that greater stress is not laid on his 

 work for economic botany, the more, that Hooker himself rightly attached 

 the greatest importance to it. It is to his endeavours we owe the inception 

 of the Plantation-Rubber industry of to-day, and it was under his direction 

 that cinchona was introduced into India, so that quinine became available 

 to the poorest native. 



Four of his chief works, of which a brief account is given, indicate the scope 

 and character of Hooker's literary contributions. These are the Flora Antarc- 

 tica, the Flora of British India, the Genera Plantarum, and the Index Kewen- 

 sis. Other chapters treat of his personal characteristics, his position as a man 

 of science, and his connection with Darwin. 



Short biographies of this type are the more welcome as appealing to a 

 wider public than the more pretentious volumes dealing with the same sub- 

 jects, and are moreover within the purse of all. 



E. J. Salisbury. 



Applied Botany. By G. S. M. Ellis, B.A. [Pp. viii+ 248, with 67 illustra- 

 tions and 2 maps.] (London : Hodder & Stoughton, 1919. Price 

 45. 6d. net.) 



One great essential in a book written with a view to applying scientific 

 knowledge to practical life, is that it should combine simplicity of style with 

 scientific accuracy. In the book under review the first condition is fulfilled, 

 for the writer has succeeded in presenting his subject in a readable and attrac- 

 tive form which will appeal to the general reader and elementary student. 

 Unfortunately the second condition is not carried out, for the book is full of 

 inaccuracies and of half-truths that are more misleading than actual errors. 

 The statement that " the seven elements . . . are essential to the growth of 

 a green plant " (p.n) implies that other elements can be done without, but 

 the indispensable carbon, hydrogen, and oxygen are not included in the seven 

 enumerated. Again, nitrogen is not one of the elements found in the ash when 

 the plant-body is burned (p. 58), for the act of burning drives off the nitrogen 

 in combination, leaving only mineral substances behind. With regard to 

 water-culture solutions (p. 59), it is impossible to dogmatise as to the changes 



