386 
NATURE 
[ FEBRUARY 21, 1907 
with one important exception, viz. that the Gymno- 
sperms are placed after the Monocotyledons. In re- 
gard to genera and species, the ‘*‘ Flora of British 
India ’’ has for the most part been followed. 
The descriptions of the commoner and more 
important species are printed in large type, and the 
information regarding them is given in three separate 
paragraphs. The botanical name, the references to 
other books, and the vernacular names occupy the 
first paragraph; the second contains the description ; 
and in the third, printed in smaller type, will be 
found the distribution of the plant in and beyond 
India, the time of flowering, and other information. 
The botanical descriptions occupying the second para- 
graph, though sometimes rather brief, are very much 
to the point. There is, however, a want of uniformity 
in the punctuation, which tends in many instances 
to prevent the essential points of the description from 
catching the eye. The use of a different type for 
the names of the principal organs, such as calyx, 
corolla, stamens, ovary, &c., would have answered 
the purpose to some extent. 
The order Dipterocarpaceze, which contains some 
very important timber trees, and others which yield 
valuable oils and resins, has been specially studied 
by the author.’ In this book he describes nine genera 
and thirty-seven species. Of the large family of 
Leguminosez, fifty-one genera are included. The 
oaks number thirty-seven species, the majority of 
which are restricted to the eastern Himalaya, Burma, 
and the Malay Peninsula; only seven extend to the 
western Himalaya, and not one has been recorded 
from the western peninsula. Of palms, twenty 
genera and eighty-nine species are described. The 
bamboos, which constitute a distinct tribe of the large 
and important family of grasses, have been very 
carefully done; fourteen genera and 102 species are 
mentioned. Of the Conifer, nine genera and 
twenty-one indigenous species are described. 
A serious drawback in the get-up of this book is 
its excessive weight. Having decided to use such a 
very heavy paper, it might yet have been arranged to 
divide the book into two equal-sized volumes. This 
would have made each volume so much more con- 
venient for handling than is the present book. 
ieee 
A HANDBOOK TO THE MICROSCOPE. 
The Principles of Microscopy; a Handbook to the 
Microscope. By Sir A. E. Wright, F.R.S. Pp. 
xxii+250. (London: Archibald Constable and Co., 
Ltd., 1906.) Price 21s. net. 
HE author of this book is a skilled pathologist, 
and, therefore, necessarily a practical master of 
the manipulation of a microscope, at least in the case 
of transparent objects. He has probably arrived at 
his views on the microscope by prolonged and varied 
practice, and by independent thought, rather than by 
studying the work of others. He thinks the reader 
may find a grievance in the number of newly-coined 
lii., part vi.; also in 
1 See in Engler and Prantl, *‘‘ Pflanzenf.” vol. 
Journ. Linn. Soc., vol. xxx., p. 1. 
NO. 1947, VOL. 75 | 
words which he employs; but in a special subject no 
one should object to technical terms, without which 
science would indeed involve circumlocution, so long 
as a new technical term is carefully defined. 
Sir A. E. Wright labours under heavy self-imposed 
difficulties. He always seeks to avoid a mathematical 
sign, the use of which as a substitute for speech can 
be defended, he says, ‘‘only in the case of the 
inarticulate classes of the learned.’’ He ignores the 
fact that speech, whether in sound or in black and 
white, is as much sign as mathematical expression 
is sign, and nothing like so accurate. 
The reader of the book may therefore profitably 
bear in mind that the work is an exposition of the 
author’s own views and explanations of results which 
often are unquestionably true but sometimes admit 
of doubt. 
The book is full, very full indeed, of beautifully 
executed diagrams; but conclusions are rather hastily 
drawn from them, and the reader is often left to 
derive his proof from due consideration of them rather 
than from detailed explanation. We can well under- 
stand that a beginner will not be quite satisfied, but 
we recommend him to persevere, as he will certainly 
find many practical rules as to the use of condensers 
in variously illuminating microscopic objects, and 
experiments illustrating these rules in a very com- 
plete way, plainly described and easily executed. A 
small diffraction grating is supplied with the book. 
The first five chapters are devoted to the considera- 
tion of the object, its visibility, and the differentiation 
of its details as depending upon its preparation in 
mounting and staining, and upon its illumination. 
The author strongly and reasonably urges the view 
that it is from this side of the microscopic problem 
that important new discoveries will spring, rather 
than from improvements in technical optics. To 
differential staining he prophesies a valuable field of 
work in the future. 
The second part of the book treats, in what seems 
to us an original way, of the microscope itself and of 
the optical matters connected with it. The author 
conceives the passage of light through a lens system 
as divided up into vistas composed of cones of light. 
The object, a small one, is at the vertex of a cone 
the base of which is the aperture of the first lens 
encountered. The second cone has the same base as 
the first, but its vertex is in the first image. The 
vista is completed at the real image, even if two lenses 
are employed before its formation. We thus have the 
opening limb and the closing limb, the pole of origin 
and the terminal pole, and the waist, of a vista, intro- 
duced as technical expressions. One vista may suc- 
ceed another, and we may have a catena of vistas. 
Thus we may have a condenser vista starting with 
the source of light and terminating at the stage, an 
objective vista beginning at the stage and ending 
between the lenses of the Huyghenian eyepiece, and 
an eyepiece vista starting at the last-mentioned place 
and ending on the retina of the eye, forming a catena 
of three vistas. 
This plan the of representing 
has advantage 
