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_ Principles and Practice of Butter-Making. By Dr.G. L. 
~ McKay and Prof. C. Larsen. Third edition, largely 
rewritten. Pp. xiv+4o5. (New York: J. Wiley 
‘and Sons, Inc. ; London: Chapman and Hall, Ltd., 
1922.) 155. net. 
Tue volume under notice is the third edition of one of 
the best-known American books on commercial butter- 
making ; it deals with the subject with great thorough- 
_ness, and contains information which has been collected 
from the best sources. The introductory chapters give 
an account of the composition of milk, its secretion, 
and the conditions which influence secretion. Next 
come the properties of milk, and these are followed by 
an account of the changes which milk undergoes when 
In an account of the peculiarities of butter 
fat, stress is laid upon the great value of this fat in 
nutrition, owing to its content of the fat soluble 
vitamin A. There are chapters on the enzymes and 
bacteria found in milk, and the causes which induce 
variations in the percentage of fat. 
_ Sampling and testing of milk and cream, both from 
the point of view of fat content and suitability for 
_ butter-making, are dealt with, and the best creamery 
methods for the estimation of fat in butter are given; 
while there are also chapters dealing with modes of 
_ payment for milk and cream delivered to the factory. 
The various types of separators and the best means 
of separating milk naturally occupy a prominent place, 
and the preparation of the cream for churning is 
fully discussed. Excellent chapters are written upon 
the churning, working, washing, and finishing of 
_ butter from the point of view of creamery practice. 
Packing and marketing of butter; defects and their 
_ ¢auses; judging and grading; storing, particularly 
- cold storage (descriptions of the plant are also given), 
are all dealt with fully. 
Handbook of Commercial Geography. By Geo. G. 
Chisholm. New edition. Pp. xvi+824. (London: 
Longmans, Green and Co., 1922.) 25s. net. 
Att geographers and economists will welcome this new 
edition of Mr. Chisholm’s well-known work with its 
scrupulous accuracy of detail. The previous edition 
was published eleven years ago: the present, a ninth 
edition, was almost ready when war broke out in 1914. 
_ The necessary delay in publication has enabled Mr. 
Chisholm to revise the book according to the present 
condition of the world. The book has been reset 
throughout, which has allowed the incorporation in 
the proper places in the text of the matter in several 
of the introductions of earlier editions, and the chapter 
on trade routes. The section on the British Isles has 
been extended considerably. Several new maps have 
been added including rainfall and actual temperature 
charts. The valuable statistical appendices have been 
revised to 1913 and increased in number, A new 
feature is a long list of alternative geographical names. 
While the book has grown, its well-known features 
remain unchanged, and few works of reference are 
- better arranged or indexed than this standard volume 
on commercial geography. It is a monument of pains- 
taking research, clear thinking, and encyclopedic 
NO. 2777, VOL. 111] 
NATURE 
77 
knowledge, indispensable not only to every serious 
student of geography and economics, but also to all 
engaged in trade and commerce. 
The Canary Islands: Their History, Natural History, 
and Scenery : An Account of.an Ornithologists Camp- 
ing Trip in the Archipelago. By D. A. Bannerman, 
Pp. xvi+365+pl. (London: Gurney and Jackson, 
1922.) 30s. net. 
Tue problems presented by insular faunas and floras 
are of the greatest interest both to the student of geo- 
graphical distribution and to the geographer. Chapters 
V. and VI. of this rather uncomfortably heavy book 
deal respectively with the affinities and origin of the 
Canarian flora, the modes of dispersal of the trees and 
plants, the distribution of animal and bird life in the 
Canary Islands, and some problems which they suggest. 
The author gives numerous examples of the influence 
of complete isolation on the differentiation of birds no 
longer able to interbreed with the continental stock 
from which they sprang; and in some cases, e.g. that 
of the Fuerteventura bustard, is able to suggest how 
the local conditions may have contributed towards the 
selection of geographical subspecies. The chapters on 
the origin, geology, and physical characteristics of the 
islands are convenient summaries for the general 
reader, while references to larger works and original 
papers will enable those who wish to consult the first- 
hand authorities. 
Les Maladies ‘parasitaires des plantes (Infestation- 
Infection). Par M. Nicolle et J. Magrou. Pp. 199. 
(Paris : Masson et Cie, 1922.) 8 francs. 
Two doctors of the Pasteur Institute have collabor- 
ated on the production of a text-book chiefly for the 
benefit of the medical profession. The ground covered 
is very wide, including diseases due to both insects 
and fungi. Part I. deals largely with gall formation, 
with short chapters on acarids and nematodes. The 
remaining parts give an outline of the diseases due 
to phanerogams, fungi, and bacteria, with a general 
discussion of such questions as virulence of attack and 
resistance to disease. The complete absence of illus- 
trations is a very serious drawback, even though it 
be considered necessary on account of cost. A further 
disadvantage is the lack of a bibliography, which 
would partly have compensated for the very brief 
treatment of each subject. In other ways the book 
is well produced and will serve a useful purpose in 
making information on plant diseases available to 
medical men. 
Clocks and Watches. By G. L. Overton. (Pitman’s 
Common Commodities and Industries Series.) Pp. 
ix+127. (London: Sir Isaac Pitman and Sons, 
Ltd., 1922.) 35. net. 
Mr. OvERTON has given us a most useful and interesting 
volume, describing the gradual evolution of time- 
pieces from the early water clocks, through the balance 
clock, down to the modern pendulum clocks and 
chronometers. There are many illustrations, and the 
various methods of compensating for temperature are 
described in plain non-technical language. In addi- 
tion there are details, probably new to many readers, 
relating to the striking mechanism of clocks and of 
repeater watches. The latter are stated to have come 
