314 
point of view of efficiency. “An efficient process 
is one in which the available results exceed the 
expenditure” (p. 4); and the work is an at- 
tempt to analyse the various forms and sources 
of efficiency into a few. elemental principles. 
“While the book has been cast in a form adapted 
to general reading, groups of exercises have been 
inserted which, it is hoped, will add to its value 
if it is used as a text-book in any institution where 
the principles of efficiency are taught.” 
Surely it is only in America that we could have 
a professor of efficiency. From the preface we 
also learn that, since the importance of investigat- 
ing the elements which constitute fitness, that is, 
efficiency, becomes evident as soon as the prin- 
ciple of the survival of the fittest is recognised, 
the leading ideas of the book were suggested by 
the reading of Herbert Spencer. Many important 
details have been obtained from the publications 
of the Efficiency Society and the works of various 
modern writers. 
The most primitive and, in a sense, fundamental 
source of efficiency is the act of re-use or repeti- 
tion, and human progress in general is marked 
by an increasing amount and by higher forms of 
re-use (p. 31). A superior efficiency to more or 
less haphazard re-use is attained by the “unit 
and multiplier principle” treated in chapter iil. : 
“A unit is any entity used manifoldly in space 
or time or in any relation. The multiplier ex- 
presses the number of manifold uses made of a 
unit” (p. 50). This principle may be extended so 
as to form a still more general agent of efficiency, 
that of the “group,” and this is dealt with in 
chapter iv. The group is so fundamental in its 
nature that the other primal sources of efficiency 
may be regarded as various methods of using the 
group. Groups may be used not only singly, but 
also in combination, with a corresponding increase 
of efficiency (chapter v.). It is often a source of 
efficiency to substitute for a given system of 
groups a series of groups or “orders” of the 
system (chapter vi.). The use of an object or 
objects external to a given domain as a means 
of obtaining results by forming new and large 
groups is the source investigated in chapter vil. 
Chapter viii. deals with sources obtained by the 
perceptions of diversities and of uniformities. 
After a study (chapter ix.) of the aims and ends 
of efficiency processes, chapter x. contains a good 
treatment of symbolism as an agent of efficiency, 
and here pp. 174-175, 177, 185, 187 (cf. p. 359) 
seem especially noteworthy. The other chapters 
are on the principle of directive action, the study 
of speed and rhythmic methods as means to effi- 
ciency, the principle of “dialectic” or unexpected 
discovery, the study of limitations of processes, 
NO. 2377, VOL. 95] 
NATURE 

[May 20, 1915 

the removal of waste and error, and the combina- 
tions of efficients. Chapter xviii. deals with appli- 
cations to psychology, education, sociology, busi- 
ness, art, ethics, and religion. Finally, there are 
appendices on “The Categories and a General 
Philosophy of Life” and a ‘“ Historical Survey.” 
The book is rather obscurely written, but con- 
tains very much valuable illustrative material. 
d. 
OUR BOOKSHELF. 
Elementary Human Biology. By J. E. Peabody 
and Dr. A. E. Hunt. Pp. xii+194. (New 
York: The Macmillan Co.; London: Macmil- 
lan and Co., Ltd., 1915.) ,'Price 4s. 
Unper this somewhat curious title the two 
authors, American schoolmasters, have produced 
a manual which deals with elementary hygiene. It 
is evidently written for children, for the pronuncia- 
tion and derivation of comparatively simple words, 
such as involuntary and ventilation, are given. It, 
however, manifests a curious lack of perspective, 
for while it contains simple exercises which teach 
young pupils the reasons for rules of health, such 
us cleaning the teeth, masticating the food, and 
washing the skin, it also deals with elaborate 
details for comparing bacteriologically with Petri 
dishes the air of a room after sweeping it with a 
broom, and after the use of a vacuum cleaner. 
One home exercise which with unconscious humour 
is marked optional consists in chewing popped 
corn and noting that it becomes sweet during the 
process. The conditions of American life are so 
often different from those in this country, for 
instance, in the matters of heating and ventilating 
houses, that we doubt whether the present book 
will profitably replace the many excellent text-books 
on hygiene we already possess here; the same 
may be said in relation to subjects such as profit- 
able housekeeping and cooking. Even if the 
English child or his parent overcomes the difficulty 
of converting dollars into shillings, we doubt 
whether they will be much enlightened by such 
words as skillet, round steak, and string beans. 
A few of the many errors noted are: that milk- 
sugar is changed into grape-sugar by heating it 
with Fehling’s solution; that the saliva forms 
dextrose from starch; that nerve impulses travel 
too ft. per second; that Nissl granules in nerve 
cells appear as a result of fatigue; that the 
epiglottis closes as a lid on the larynx during 
swallowing; that peptone is the end-product in 
digestive proteolysis; that Sylvester’s method for 
artificial respiration is the best. Children, it is 
true, require teaching to be simple, but they 
deserve that it should be accurate. W. D. H. 
Inorganic Plant Poisons and Stimulants. By Dr. 
W. E. Brenchley. Pp. ix+110. (Cambridge: 
At the University Press, 1914.) Price 5s. net. 
Miss BreNCHLEY has set herself a difficult task in 
attempting to deal with problems such as are in- 
dicated in the somewhat ambitious title of her 



