January 8, 1914] 
NATURE 
525 
mercial success in the near future. Ihe book ends 
_ with a bibliography giving 179 references to the | 
original literature. 
(3) The title of this work very accurately repre- 
sents its contents; it is in no sense a text-book 
of plant chemistry, though it is intended for 
studenis of vegetable physiology. The plan 
adopted by the authors is to single out various 
groups of substances because they occur in plants, 
and to give some idea of their chemistry. Refer- 
ence is usually. made to the mode of occurrence 
of the particular compound, and occasionally to its 
biological significance or economic importance. 
From the point of view of the botanist, especially 
the junior student, the result is a valuable com- 
pilation of facts which were previously only to be 
found widely scattered. The authors are to be 
congratulated on the extent of their reading and 
the large aniount of pertinent matter which they 
have introduced, much of which has not hitherto 
been found in text-books. 
Viewed, however, from a somewhat higher 
standard of criticism, the book is disappointing. 
It lacks stimulus and feeling, both on the chemical 
and on the botanical side, and although informa- 
tive ii is not sufficiently critical to guide the user 
on just those questions where he needs informa- 
tion. If chemistry is to be of real aid to the 
biologist, he must realise its broader issues and 
acquire some chemical feeling. This it is impos- 
sible to gain from a book dealing with the reac- 
tions and properties of selected substances, and 
the introduction of such methods of teaching 
chemistry to biologists is to be deprecated on all 
grounds. 
The writers are at their best in some of the 
more advanced sections, those dealing with the 
tannins and with plant pigments being admirably 
done. The other chapters are devoted to fats, 
carbohydrates, glucosides, nitrogen bases, col- 
loids, proteins, and enzymes. 
© (4) Dr. Wohlgemuth in his preface claims to 
have ‘collected together all the experimental 
methods which are of use for the study of enzymes, 
but we fear he will find it difficult to establish 
his claim. Indeed, the book is disappointingly 
Superficial, the more so as there is a real need for 
it just at present. Many of the best and most 
gener .ilv used processes are entirely ignored, and 
there are far too many inaccuracies and loose 
‘statements. In particular, the author appears to 
have paid no attention at all to the very large 
bulk of English and American work on the sub- | 
ject, cither in the original or in the excellent 
‘abstracts in the German journals which must have 
been available to him. con 
_ The carbohydrate enzymes are very incom- 
= NO. 2306, VOL. 92] 
7 
‘ 
7 
pletely treated, and the same applies to diastase. 
The estimation of this enzyme is so important for 
the brewing industry that it has been very thor- 
oughly studied, and methods of great accuracy 
lave been elaborated, for which we look in vain. 
Emulsin scarcely receives mention, in spite of 
its importance in plant physiology, and of the 
newer work on it we find not a trace, The in- 
formation about urease is equally scanty. The 
author is more lengthy and presumably more at 
home on the pathological side of the subject, and 
he appears to cater specially for medical men 
who propose to make the detection of enzymes of 
advantage in diagnosis. It is desirable to em- 
phasise the danger of this practice—the technique 
of enzyme identification is not easy, and insufh- 
ciently qualified workers are prone to obtain mis- 
leading results. Physiological chemical literature 
is already burdened with so much that is incorrect 
that no encouragement should be given to prac- 
tices which are likely to lead to a continuance of 
the evil. E: EAs 
THE REGULATION OF NAVIGABLE 
RIVERS. 
The Improvement of Rivers. By B. F. Thomas 
and D. A. Watt. In two volumes. Pp. xv + 
749+76 plates. (New York: John Wiley and 
Sons, Inc.; London: Chapman and Hall, tds 
1913.) Price 31s. 6d. net. 
HIS is the second edition of a book published 
in New York in 1903. The authors are 
assistant engineers in the service of the United 
States, and have drawn to a considerable extent 
on their personal experience of works carried out 
in that country. The subjects dealt with are :— 
Chap. i., The characteristics of rivers; ii., Regu- 
lation of river channels; iii. and iv., Dredging 
and Snagging; v., Embankments and their pro- 
tection; vi., Levees; vii., Storage reservoirs; 
vili., The improvements of the outfalls of rivers. 
The second part relates principally to the canalisa- 
tion of rivers. Tidal rivers are not dealt with. 
The text is accompanied by a great number of 
illustrations explanatory of the works described. 
These two volumes contain much useful informa- 
tion relating to the subject dealt with, and are 
well worth the study of engineers engaged in this 
class of work. 
The authors direct attention to a fact that should 
be borne in mind by engineers engaged in river 
training, that experience has shown that although 
water is a fluid element without cohesion, influ- 
enced by the laws of gravitation, yet it cannot be 
; made to flow in any desired direction unless the 
training works are carried out subject to rules 
