242 
NATURE 
[Fuly 24, 1873 
tinuum, the regula may be regarded-as the discretum ; 
but it were a false conception, that of the continuum as 
made up of an infinite number of discre¢a (regule) infi 
nitely small. Such continuum is but the exemflification, 
proexumbration, externalisation of the regula,” &c. (p. 
116.) Winds 
OUR BOOK SHELF 
Sunior Course of Practical Chemistry. By H. E. Roscoe, 
B.A., F.R.S., &c., and Francis Jones. (London : Mac- 
millan and Co.) 
THE work now before us represents the course of practical 
chemistry carried out by students entering the Owens 
College Laboratory. It commences with the preparation 
of the ordinary gases, which are, if anything, too shortly 
described ; and then proceeds to the subject of blowpipe 
analysis and the preliminary examination of simple sub- 
stances, and afterwards to the reactions of metals, 
&c., and qualitative analysis itself. The book does not 
deal in any way with theoretical chemistry, but the student 
is referred to Prof. Roscoe’s “Lessons in Elementary 
Chemistry” for any explanation of this kind. This, of 
course, necessitates a considerable amount of extra read- 
ing, more particularly in the earlier portions of the book. 
The course of qualitative analysis, and so forth, through 
which the student has to pass, seems to be very similar 
to that which is now in use in most of our laboratories. 
The various experiments, reactions, &c., are as a rule 
clearly described, but we notice one or two which would 
undoubtedly be better for some slight alteration and ad- 
dition ; thus, on p. 59, we find the following given as a 
method of testing for Baric sulphate :—‘‘ Barium sulphate 
fused with Na, Co, and HCl added, yields BaCl, (flame 
coloration green), precipitated by SrSo, solution.” Now 
we think that there is a strong probability that a student 
proceeding as directed in the book would again form the 
original Baric sulphate, and he would certainly not obtain 
any precipitate with Strontic sulphate solution, and 
probably would not obtain the green colouration. The 
same method is also given for the detection of Strontic 
sulphate. Another instance in which we think that clear- 
ness has perhaps been sacrificed to brevity is in Table A, 
but with a teacher at hand there need be little fear but 
that the student will easily overcome such minor difficulties. 
In fact the book is written with the desire to aid the 
teacher in his work, and not to dispense with his ser- 
vices altogether ; in the former we think the book is very 
successful, but we do not believe that a student could well 
work through the book without such aid. 
A number of well-selected questions is appended at the 
end of the book. They seem well adapted to test the 
student’s knowledge of his work, and will in this way con- 
siderably lighten the teacher’s labours. 
We must also not forget to mention in terms of high 
praise the three short rules for the guidance of students, 
which are appended by Prof. Roscoe at the end of the 
preface, and we hope that every student who works by 
this volume will lay them to heart, and practise them 
with all sincerity. 
The title of this book, “ Junior Course,” &c. scarcely 
conveyed to our minds exactly what we have found the 
book to be. It is more advanced than we anticipated, 
and yet, perhaps, it is not a thoroughly complete manual 
of qualitative analysis, although nearly so; but we must 
still thank the authors for a clear and succinct little 
manual, which will no doubt prove very useful to both 
teachers and students, 
The Philosophy of Evolution. An Actonian Prize 
Essay. By B. T. Lowne. (Van Voorst.) 
THe author of this short sketch of the theory of evolu- 
tion is already favourably known by his treatise on the 
anatomy of the Blow-fly, a strictly anatomical work, 
abounding in detail, and not going beyond the region of 
fact. We can scarcely congratulate him, however, on 
the success of his theoretical attempts, as many of them 
are but weakly based, and others lead to very unreason- 
able deductions. 
In the discussion of the variations which, according to 
the Darwinian hypothesis, give rise to the development — 
of new forms, Mr. Lowne terms the greater tendency 
possessed, as he states, by some animals, to vary, 
plasticity, and the less tendency among others, rigidity ; and 
he considers that these characters, plasticity and rigidity, 
are capable of being transmitted from generation to 
generation like other hereditary characters. At first 
sight this may appear highly probable, but to any one 
who considers the subject, it will be evident that it is 
based on an erroneous conception of the nature of that 
so frequently employed, but still ill-understood expression, 
variation. For the assumption of the existence of a 
struggle, together with the concomitant “ Survival of the 
Fittest,” means that the possible variation in a particular 
advantageous direction is tending to a limit, or in other 
words, that the continuation of the struggle is. correlated 
with a tendency to the reduction to a minimum of the 
power to vary, for directly any advantageous tendency is 
developed, it is immediately run upon and exhausted. 
The chapter on nutrition contains more than one pro- - 
position open to criticism; the function is incorrectly 
defined, and the ultimate destination of foods which is 
said to be in three directions, namely of nutrition, energy, 
and excretion, is very misleading. But it is in the expla- 
nation of the formation of the antlers of the Deer that a 
theory is given, which is not exceeded in rashness and 
lack of foundation by any lately put before the scientific 
world ; the following is a sketch of the argument :— 
Herbivorous animals, specially ruminants, take into their 
system a superabundance of salines, the excess of which 
the kidney is not sufficiently developed to eliminate ; 
consequently, on an axiom laid down by Sir J. Paget 
(who would be one of the first to object to this abuse 
of his words) that every part of the body may be looked 
upon as an excretion to every other part in highly 
complex organisms, this excess is got rid of by the 
development of the antlers, which contain a large amount 
of calcium salt, and are shed every year: the females 
have no horns, because in them the excess of salts is 
employed in the formation of the bones of their progeny. 
Such being the case, we do not know how Mr. Lowne 
explains the elimination of the salts in the Cavicorn 
ruminants, and their non-development in the males of 
all other herbivorous animals. 
We cannot agree with our author in his attempt to 
derive all the higher forms of animal life from aquatic 
ancestors. Upon this supposition he attempts to prove 
that the Penguins and Auks belong to the early type of 
birds, and that they show marked reptilian affinities, but — 
as they do nothing of the kind, his endeavour is worse than 
feeble. We are quite unable to see how the view “ that the 
aquatic penguins belong to an early type of birds has 
been materially strengthened of late by Professor Marsh’s 
remarkable discovery of an Ichthyornid type of birds in 
the Cretaceous shales of Kansas.” 
The elaborate markings of the flint shields of the 
Radiolaria and Diatomacez being somewhat like the 
curves which are produccd on the surface of a vibrating 
metal plate, on which sand has been scattered, we are 
told that “nothing appears more probable than that 
similar points of vibration and rest exist upon the surface 
of these shield-forming organisms, and that the excreted 
silica which forms their shields comes to rest at the nodal _ 
points.” This explanation is bold, to say the least, con- 
sidering the very different circumstances under which the 
results are produced. Mr. Lowne should try to produce 
the curves or the vibrating metal plate under water. 
