394 
NATURE 
[JuNe 20, 1912 
sitic life, and so on. In a few lines often, with 
the aid of clear figures, he makes his point; thus 
the Echinococcus tapeworm is very small and 
with few joints, therefore relatively less prolific 
than usual, therefore (an indirect ‘“therefore,’’ of 
course) the bladder-worm stage has taken on a 
prolific multiplying function, which is most un- 
usual. The studies of earthworm and pond-mussel 
are admirable, the familiar facts being used to 
illustrate generalideas. In the chapter on Crusta- 
ceans there is naturally a discussion of “ moulting’,”’ 
of transformations of appendages, of special 
adaptations as in Leptodora, of larval stages, and 
so forth; while in the final chapter, which deals 
with insects, the author is very happy in his illus- 
tration of the adaptation of structure to particular 
conditions of life, which is, indeed, the general 
theme of the whole book. Prof. Deegener says 
in his preface that he has no wish to pander to 
easy-going readers who wish to be amused, but 
none the less his book is as interesting as it is 
instructive. The illustrations are mostly good; 
we wish, however, to direct attention to the fact 
that a number of well-known figures are referred, 
not to their original sources, but simply to the 
text-book from which they have been directly 
taken. This common practice seems to us to be 
very undesirable. 
(3) Dr. Renner and Prof. Maas supply the 
botanical and the zoological parts respectively of 
an introduction to biology, primarily designed for 
teachers in the ‘‘Mittelschule.” In some respects 
it may be put alongside of the late Prof. T. J. 
Parker’s well-known “Elementary Biology ”—a 
book which it would be hard to beat—but there 
are interesting differences in plan and method. 
The botanical half starts off with the parts of the 
plant, working down to the cell; then follow chap- 
ters on the structure and life of Thallophytes, 
Mosses and Ferns, and Flowering Plants; another 
section deals with nutrition in green plants and 
in saprophytes; the remaining chapters discuss 
inter-relations, habitats, power of movement, and 
the relations between plants and their environ- 
ment. The book is full of interesting material, 
which is clearly and tersely dealt with; and the 
text is illustrated by a large number of original 
figures, which it is a relief to see. Dr. Maas 
begins again with the animal cell and goes on 
to the Protozoa. From animal organisation at the 
single cell level he proceeds to the “tissue-level ” 
in Ceelentera, and to the “organ-level ” in worms. 
After a condensed chapter on classification and 
the evidences of evolution, the book takes a dif- 
ferent turn, dealing with the various systems, 
nutritive, respiratory, vascular, excretory, mus- 
cular, nervous, and sensory. It culminates in 
NO. 2225, VOL. 89] 
short chapters discussing development, regenera- 
tion, fertilisation, heredity, and the factors of 
evolution. As one would expect from Prof. Maas, 
this zoological introduction to biology is a sound 
piece of work, clear and up-to-date, but it will 
surely require a good deal of boiling down before 
being naturally suitable for the erudite youths of 
the “Mittelschule.”” It appears to us that more 
“natural history,” and less analytical biology, 
would have been more appropriate, but this, of 
course, was not what Dr. Maas intended to supply. 
Most of the illustrations are good and many of 
them fresh. ; 
(4) Prof. Timiriazeff’s “Life of the Plant” was 
delivered as a course of lectures in Moscow in 
1876, and has passed through seven Russian 
editions. Its aim was to make the life of the 
plant intelligible to a popular audience, and the 
author expressed in his preface to the first 
Russian edition his sense of the difficulty of his 
undertaking. Ina popular exposition it is impos- 
sible to tell the whole truth, and with a young 
science like plant physiology it is difficult to tell 
nothing but the truth. Moreover, in popular 
exposition, the expert must step back a little from 
his science to see what it looks like at a distance. 
Prof. Timiriazeff thinks that his book “not only 
in its general tendency, but even in the choice of 
matter and in the order of exposition,” may 
“answer the present requirements cf English 
schools as formulated by so eminent an authority 
as Prof. Armstrong.” 
When a master of a craft condescends to write 
popularly, we look out for something “big,” and 
there is no doubt that Timiriazeff’s book stands 
head and shoulders above most of its fellows. It 
has a wide sweep, beginning with the analysis of 
flour and culminating in the Darwinian theory ; it 
is very objective in its treatment; it skilfully 
utilises the familiar, and works Socratically ; 
it is demonstrative rather than informative, 
giving the reader the delicious illusion that he is 
himself at work building up the science of plant 
physiology; it has a masterly simplicity of style 
to which the translator has surely done justice. 
The book will be of great service to teachers, in 
showing, for instance, what a lot can be made of 
relatively simple experiments; in showing, too, 
how a certain restraint and severity in the process 
of intellectual construction leads in the end to a 
very vivid picture of the living plant. It is after 
the patient course of induction that we come to 
perceive, in the depths of numberless cells, “ proto- 
plasm in ceaseless motion like the tide of the sea ”’ ; 
“the root buried deep in the ground, imbibing its 
liquid food and corroding the particles of the soil 
all along its course of many miles ”’; “the insigni- 
