426 NATURAL SCIENCE [December 



of plant physiology in England, where he thinks it is seriously retarded 

 by the lack of suitable books. He admits the excellence of Francis 

 Darwin's " Practical Physiology of Plants," but seems to think that an 

 English work on more advanced and comprehensive lines is needed. 



Prof. Detmer's " Praktikum " covers nearly the whole field of ex- 

 perimental plant physiology in the widest sense, ranging from the 

 rheotropism of Myxomycetes to the breaking stress of bast fibres, and 

 from unpalatability with snails to emulsion figures simulating proto- 

 plasm. Yet the whole does not strike one as being, in the highest 

 sense, a book — an expression of a personality — as does the " Experi- 

 mental Physiologie " of Sachs, or even the " Praktikum " of Prof. 

 Strasburger ; but it has rather markedly the air of being pieced to- 

 gether. It is indeed an encyclopaedia of methods, which have been 

 carefully overhauled — an immense piece of work — by the author. It 

 seems as if it ought to be very valuable as a work of reference, yet one 

 is not quite sure what class of student will refer to it. It is no doubt 

 really intended for the small number of advanced students who are 

 about to undertake research on the physiology of plants, and so gives 

 an account of the stock methods of investigation. 



The experiments are grouped, in logical sequence, into five sections, 

 viz., the Food of Plants, the Molecular Forces in Plants, the Metabolic 

 Processes in the Plant, Movements of Growth, and Movements of 

 Irritation. The successive experiments are not categorically limited, 

 but are linked together by theoretical and expository paragraphs, so 

 that the book can be read continuously ; but this involves so much 

 additional space that in many experiments small details have to be 

 omitted, the neglect of which will prevent the experiment being suc- 

 cessful on first trial. 



The second German edition (1895) is nearly one-third longer than 

 the first edition (1888), has been largely re-written, and contains a 

 short appendix on recent views on the ascent of water. 



The weakest section in the present edition is that on the applica- 

 tion of the polariscope. It is said to be ' very instructive ' to investi- 

 gate the phenomena exhibited in polarised light by starch grains 

 (which, however, should be mounted in Canada balsam for this 

 purpose, not in water) ; but surely, beyond the pretty effects, the 

 student learns nothing from his observation but the fact that starch 

 grains are anisotropic. This may be clue to a remote crystalline 

 structure or to internal tensions. The latter hypothesis is not men- 

 tioned though it might easily have been illustrated experimentally. 

 As a further obscurity, ' gypsplattchen ' has been translated in the 

 English edition as ' plates of gypsum ' (p. 115). This should of 

 course be plates of selenite, which have special optical properties. 



The most complete sections are those on Eespiration, which have 

 been considerably expanded, and to which Prof. Detmer and his 

 pupils have contributed original work. 



The English edition is translated without alteration or addition 

 from the second German one. There is something to be said for 

 retaining unchanged the appendix, which gives an annotated list of 

 the German dealers in, or makers of, the scientific apparatus described 

 in the book ; but a patriotic editor might have indicated where some 

 of the articles could be obtained in this country. It is not necessary 



