426 NATURAL SCIENCE "c [Decemttict 
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 due 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 Respiration, 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 
