i895. SOME NEW BOOKS. 281 



which lias been reached in biological science, such books as the 

 present would amply suffice. A good deal has been done within the 

 last ten years on starch, its chemistry, its origin, and its meaning in 

 the nutrition-processes of plants, and although Sachs' idea that it 

 represented the first formed carbohydrate in the cells of the assimi- 

 lating green leaf is no longer tenable, it is equally certain that as an 

 easily-worked reserve substance it is of the utmost importance in 

 plant-physiology. Dr. Meyer's criticisms and the account of his 

 exhaustive investigations are arranged under five headings. In the 

 first, on the chemistry of starch and diastase, we have an historical 

 and chemical account of the compounds of which the grain is com- 

 posed, or which are formed by the action upon it of the diastatic 

 ferment. The micro-chemical reactions are also discussed. The 

 second part, on the physical characters, contains arguments and 

 experimental evidence in support of the view that starch grains are 

 sphaerocrystals of amylose and amylodextrin, and concludes with an 

 account of the structure and growth of the grains, in which Nageli's 

 theory of growth and intussusception is severely criticised. Part III., 

 the biology of the starch grain, is a full account of its life-history, 

 a propos of which we find a discussion of the part played by the 

 different constituents of the chloroplast. Part IV., " Biologische 

 Monographien," is a series of short monographs on the starch grains 

 of the resting shoots of Adoxa moschatellina, the endosperm of barley, 

 and a few other examples. Finally, we have a few pages on starch 

 grains as constituents of living protoplasm. We must not omit a 

 word in praise of the nine plates which, with the wood-cuts, form a 

 very helpful addition. 



Botany Books. 



Das Pflanzenphysiologische Praktikum. Anleitung zu pflanzenphysiologischen 

 Untersuchungen. By Dr. W. Detmer. Second edition, enlarged and revised. 

 8vo. Pp. xvi., 456, with 184 wood-cuts. Jena : Fischer, 1S95. Price 9 marks. 



Professor Detmer's practical exposition of plant-physiology is so 

 well known, and has proved so valuable and trustworthy a guide on 

 the subject, that the appearance of a second edition is not a matter 

 of surprise. Lecturers on the subject and students of the life- 

 processes of plants will welcome the new issue, and rejoice that 

 Professor Detmer has been able to add so much that is new and of 

 interest. 



Analytical Key to the Natural Orders of Flowerixg-plants. By Franz 

 Thonner. Svo. Pp. vi., 151. London: Sonnenschein, 1895. Price 2S. 



If we read his preface aright, Mr. Franz Thonner, who writes from 

 Dresden, has compiled this little book for the use of English colonists, 

 to enable them to run down to its natural order any plant in which 

 they may chance to be interested. It is, in fact, an adjunct to the 

 few and fragmentary colonial floras which we possess, by which, 

 having already found the order, the student will be able to work out 

 the genus and species. We presume this is why he uses the system 

 of Bentham and Hooker's " Genera Plantarum," — a truly excellent 

 one, — but in several respects not quite on a level with our present 

 knowledge. It seems to us that the colonist who is able to use his 

 "Flora"' will also be able to dispense with Mr. Thonner's Key, 

 which on this view seems a waste of effort. 



