MarcH 17, 1904] 
NATURE 
452i 
tion. If he refers to the reports of the British Associ- 
ation for 1898 he will find that Poulton and his | 
assistants have proved that the pupz of Vanessa 
urticae are subject to a severe struggle for existence 
from birds at Oxford and the Isle of Wight, and that | 
in this case the resemblance in colour of the pupz to 
the surroundings is of prime importance in the 
struggle. 
In the face of such evidence as this the statement | 
on p. 386 that it is pure chance which of the seeds of 
a tree or which of the eggs of an animal survives re- 
quires some better proof than we have at present before | 
it is acceptable. The evidence of Guy Marshall in his 
valuable papers on the bionomics of South African 
insects adds very materially to the support of the theory 
of natural selection, and naturalists may rest assured 
that, notwithstanding the vigour and the ability with 
which this, the latest, attack upon their trenches has 
been delivered, the defence of the theory of naturai 
selection is still intact. SypneEy J. Hickson. 
ASSAYING IN THE COLONIES. 
Metallurgical Analysis and Assaying. By W. A. 
Macleod, B.A., B.Sc., A.O.S.M. (N.Z.), and Chas. 
Walker, F.C.S. Pp. xii+318; with tog figures in 
the text. (London: Charles Griffin and Co., Ltd., 
1903.) Price 12s. 6d. net. 
{ 
HE aim of this work, as explained by the authors | 
in the preface, is to provide a ** graded course of 
work, leading from simple qualitative analysis up to 
the technical quantitative methods employed by the | 
modern metallurgical chemist,’? and is intended to 
cover a period of three years’ laboratory work. 
The book is divided into three parts, of which parti., 
containing 50 pages, deals with qualitative analysis 
and the properties of gases, and part ii., containing 
140 pages, deals mainly with quantitative analysis. 
Part ili., comprising 118 pages, is subdivided into two 
sections, the first treating of the ordinary methods of 
fire assaying, while the second gives an outline of the 
methods employed in some well-chosen examples of 
technical analyses. 
The authors do not claim any originality of matter, 
but simply novelty in arrangement which is adapted 
to meet the requirements of students of schools of 
mines, ‘‘ more especially of colonial schools of mines.’’ 
This distinction between colonial and other schools of 
mines is difficult to understand, for the work which 
a qualified metallurgical chemist is required to under- 
take is independent of the locality in which he has 
received his training, and if the course of study is to 
be broad and- efficient, a text-book which is suitable 
for one school of mines will be equally suitable for all. 
At any school of mines the students must be well 
grounded in the principles of assaying, so that they 
can understand, test, and practise any method that is 
subsequently presented to them. 
It is obvious, for example, that the study of assay- 
ing should be preceded by a course in chemistry, but 
this can hardly be included amongst the duties of the 
instructor in assaying. It would be better that the 
chapters dealing with such subjects as glass working, 
NO. 1794, VOL. 69] 
the preparation and properties of gases, and elemen- 
tary qualitative analysis should be omitted, and the 
matter left to the discretion of the professor of 
chemistry. Moreover, there are so many excellent 
text-books dealing with this part of the subject that 
it seems a pity that the authors should have sought 
to include it in this volume. 
Part iii. has been carefully prepared, and the explan- 
ations are invariably clear and concise. Unfortunately, 
however, it suffers from want of space, and might well 
be expanded at the expense of some of the earlier 
chapters of the book. Thus the assay of tin ores is 
dealt with in a chapter of two pages, and that of 
lead ores occupies only three pages. Silver also re- 
ceives three pages, and copper, sulphur, and mercury 
are dismissed in a short chapter of two pages. In 
| spite of this enforced brevity, however, the authors 
have made the most of the space at their disposal, and 
the methods they describe are up to date and trust- 
worthy. No pains have been spared in consulting and 
quoting from the work of recognised authorities on 
assaying, but it is doubtful whether the frequent 
reference to divergent opinions may not, in itself, con- 
stitute a source of danger. For example, the student 
who is told that the length of time required for the 
fusion of a tin assay by the cyanide method is variously 
estimated by different writers at from 3 to 30 minutes 
may be tempted to think that he also can vary the time 
of fusion within these limits, and still obtain satis- 
factory results. The importance of uniformity in 
working cannot be too strongly impressed upon the 
beginner. 
The mistakes are remarkably few and unimportant, 
and the publication of this volume tends to prove that 
the teaching of metallurgical analysis and assaying 
in Australia rests in competent hands. 
OUR BOOK SHELF. 
The Direction of Hairy in Animals and Man. 
Kidd. Pp. xii+154; illustrated. 
C. Black, 1903.) Price 5s. net. 
ALTHOUGH it is quite natural that every student should 
consider his own pet subject one of special importance, 
we cannot think that Dr. Kidd has sufficient justifica- 
tion for publishing a second work on the hair-slope of 
mammals, since the volume before us does not appear 
to carry the case materially further than was done in 
““Use-Inheritance.’’ Indeed, since the author himself 
(p. 122) is fain to admit that hair-whorls, featherings, 
&c. (as he terms the various abnormalities in the direc- 
tion of the hair) are variable, intrinsically unimportant, 
and even whimsical, we should have thought that 
enough had been made of them in the earlier work. 
If further evidence of their variability and slight 
morphological importance be considered necessary, we 
may refer to Prof. Ray Lankester’s recent description 
of the condition existing in two specimens of the olxapi, 
one of which shows a single and the other a double 
whorl on the forehead. If, however, the author and his 
publishers find the public sufficiently interested in the 
subject to absorb a second work, they have, from their 
own point of view, a sufficient justification for its issue. 
Briefly stated, Dr. Kidd’s theory appears to be as fol- 
lows. In certain mammals, notably many long-bodied 
and short-limbed carnivores, and many rodents, marsu- 
By W. 
(London: A. and 
