NATURE 
[JuLy 4, 1912 
Haecker’s. It differs from several of its analogues 
in being successfully comprehensive, dealing with 
the cytological, the experimental, and even the 
statistical methods of studying the hereditary 
relation. It says most about the first, as one 
would expect from the fact that most of the 
author’s researches have been concerned with the 
germ-cells, and least about the last, so difficult to 
expound in a general treatise; but it is a well- 
balanced book, and it displays competence and 
carefulness conspicuously throughout. It is 
surely an achievement to write an effective intro- 
duction to the science of genetics, for it implies 
familiarity with the three lines of attack already 
referred to, and it cannot be done satisfactorily by 
one who is not equally at home with botany and 
with zoology. The difficulty is increased by the 
rapid growth of the study; important researches 
follow on the heels of one another faster than most 
of us can read them. Nor is it always easy for one 
who has not been working at the subject to get a 
grip of the technical papers—whether cytological, 
Mendelian, or biometric. Hence the welcome that 
must be given to a book like this before us, in 
which the author moves with a firm step and 
guides us discriminatingly to the more essential 
facts. 
The book begins with illustrations of the facts of 
inheritance, and with a warning about the differ- 
ence between rules and laws (the latter being as 
yet very few). Then follows a short account of 
statistical methods. The second section of the 
book deals with the material basis of inheritance— 
the history of the germ-cells, their maturation and 
fertilisation, the chromosomes and their behaviour. 
The third section is devoted for the most part to 
Weismann’s contributions—his theory of the con- 
tinuity of the germ-plasm, and his scepticism as 
to the transmission of somatic modifications. The 
fourth section is experimental, that is to say, it 
deals with Mendelism. The fifth section is of 
great interest, dealing with debated questions more 
or less bound up with the question of the material 
basis of inheritance. Prof. Haecker deals in a 
masterly way with such subjects as the indi- 
viduality of the chromosomes, the processes of 
reduction, the chromosomes as vehicles of inheri- 
tance, the existence of sex-determining chromo- 
somes. The last chapter expounds a cytological 
theory of the process of Mendelian segregation. 
Appended to each of the thirty-three chapters there 
is a carefully selected bibliography. 
To our thinking, Prof. Haecker’s book is a 
remarkable success—it is clear, comprehensive, 
and fair-minded. The author is a teacher as well 
as an investigator, and he has known what to 
NO. 2227, VOL. 89| 
leave out as well as what to put in. The device 
of numerous short chapters is very effective; the 
illustrations are admirable and always of real 
service; and the temper of discussion is scientific 
throughout. 
MINERAL LOCALITIES. 
Ein Hand- und Hilfs- 
buch fiir Anlage und Instandhaltung mineralo- 
gischer Sammlungen. By Dr. W. Brendler. 
i. Teil. Pp. vilit7oo. (Leipzig: W. Engel- 
mann, 1912.) Price 20 marks. 
Mineralien-Sammlungen. 
N the first part of this work, which we noticed 
three years ago, Dr. Brendler described, 
mainly for the benefit of the amateur collector 
of minerals, the characters by which the various 
species may be discriminated, and the most suit- 
able methods for housing and displaying a 
mineral collection, and for registering and label- 
ling the specimens. The section dealing with the 
care of the specimens was particularly useful, be- 
cause the subject is not referred to in text-books 
of mineralogy. The present volume, which forms 
the second and concluding part of the work, 
covers more familiar ground, and treats system- 
atically of the mineral species, the classification 
being the same as that adopted by Prof. P. von 
Groth in his ‘‘ Tabellarische Uebersicht der Miner- 
alien.” Under each species are given the chemical 
formula, the system in which it crystallises, the 
hardness and specific gravity, the streak and 
colour, and a full list of the prominent localities 
at which it has been found, reference to the list 
being facilitated by the use of heavy type for 
countries or large districts and of spaced type 
for the actual places. 
The information is therefore an abstract of that 
contained in Dana’s ‘System of Mineralogy” or 
Hintze’s “Handbuch der Mineralogie”; but, al- 
though it might have been usefully expanded by 
some description of typical crystals and some ac- 
count of the association of the several species, it 
will suffice for the ordinary requirements of most 
collectors. At the same time, it should be noted 
that the volume is very much cheaper in price and 
handier in form than these large treatises, and, 
moreover, it possesses a very great advantage in 
an index of localities as well as one of species, a 
good topographical list being most useful to a 
collector. The names of places in Greenland 
have been carefully revised, and the meanings, in 
German, of the words are stated. 
The intention of the book is good, but the 
execution is less praiseworthy. Making every 
allowance for the difficulty of collecting and bring- 
