290 SOME NEW BOOKS [ocTroBER 
FERMENTATION. 
The Soluble Ferments and Fermentation. By J. REYNOLDS GREEN, Sc.D., 
F.R.S., Professor of Botany to the Pharmaceutical Society of Great 
Britain. Pp. xiii. +480. Cambridge University Press: C. J. Clay 
and Sons, 1899. Price 12s. 
We can thoroughly recommend Prof. Reynolds Green’s book to all who wish 
to obtain a trustworthy guide to a correct knowledge of the processes of ferment- 
ation. When we consider that it is little more than half a century since 
Pasteur discovered that the cause of alcoholic fermentation is the activity of the 
yeast plant, the strides made in our knowledge appear prodigious. There is 
hardly any aspect of animal or vegetable life in which ferments do not play some 
part. The ferments that cause our food to be digested, that produce clotting 
of the blood, that bring about oxidation, that minister to plant life in various 
ways, that are associated with the putrefactive and other changes wrought by 
bacteria, are all described with full details, and in a lucid, interesting manner ; 
the history of the subject is also well given. The distinction between the 
organised ferments, like yeast and bacteria, and the soluble or unorganised 
ferments or enzymes, such as pepsin of the gastric juice, and diastase in 
germinating seeds, is a useful one. But the difference is more apparent than 
real, for probably in all cases the micro-organisms which are called organised 
ferments perform their work by secreting soluble ferments or enzymes. The 
recent work of Buchner has certainly shown this to be the case for yeast. 
What enzymes really are, and how they produce changes in large masses of 
material without any apparent change in themselves, or in their power, are 
much more difficult points to answer; the reader will, however, find in this 
book such general questions discussed in the light of recent knowledge. The 
ferments themselves, so far as any positive statement can be made, appear to be 
real chemical substances, and in their composition are allied to the albuminous 
bodies, particularly to the class known as nucleo-proteids. The interesting 
recent work of Emil Fischer, which is very clearly described, shows a possible 
way in which such substances could produce the change known as fermentation. 
All these theories are, however, tentative ; whether they will stand the test of 
time, the future only can show. H. 
A MODEL FLORA. 
The Flora of Cheshire. By the late Lorp DE TABLEY (Hon. J. BYRNE 
LEICESTER WARREN, M.A.) Edited by SPENCER Moore. With a 
Biographical Notice of the Author by Sik MOUNTSTUART GRANT DUFF. 
Pp. exiv. + 399, with a Portrait of the Author, and a Map of the County. 
London: Longmans, Green, and Co., 1899. Price 10s. 6d. 
Cheshire botanists will welcome the appearance of this flora of their county, 
though an interval of close on quarter of a century has elapsed since the prepara- 
tion of the materials now for the first time printed. During such a period 
many changes must of necessity have taken place in details of local distribution, 
but the flora has been brought as far as possible up to date by the editor, and 
is a model of what a county flora ought to be. 
The author has devoted great attention to describing, often at considerable 
length, the physical features, soils, etc., of the specific habitats, a point of great 
biological importance, and one too often overlooked. Duly authenticated, and, 
where possible, personal records are provided of the occurrence of each species 
in each of the seven hundreds, and a striking feature of the book is the care 
expended on the enumeration and history of alien and introduced species, many 
of which are traced back to their origin in ballast heap or garden, while numbers 
