December 16,1880. ] JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 551 
the greater of necessity must be the height of the back wall, as is 
shown by fig. 99, applied to a lean-to roof to a scale of a quarter of 
an inch to a foot. It will be seen that when the angle of elevation 
is 45° the width of the house and the height of the back wall are 
equal, calculating from the base line a of the quadrant. With 
an angle of 40? the height of the back wall is diminished by 
feet, and vice versa for every 5° of arc. In calculating the 
angle it must be from the base— i.c., top of the front or side lights 
direct to a point at the same height at the back wall of a lean-to, 
or the centre of a span. I do not, however, propose to enlarge 
upon this subject, it will suffice to note that the higher the pitch 
of the roof the greater the accumulation of heat in the upper 
angle, on which account it is desirable to keep the slope as low 
as is consistent with the admission of light. The lower the 
angle the more equable the temperature at the top and bottom of 
the space enclosed ; but if too low it will tend to drip, aud a low 
pitch considerably lessens the rafter, consequently reducing the 
extent of surface available for training Vines. For structures 
where little fire heat is employed 40° is the most suitable angle of 
elevation. To avoid drip it should not be less than 30°, which 
will answer well enough for general purposes, and for early forcing 
45° is quite sharp enough.— G. Abbey. 
EEVIEW OF BOOK. 
Anatomical and Physiological Atlas of Botany. By Dr. Arnold 
and Carolina Dodel-Port. Parts 1, 2, and 3. W. & A. K. 
Johnston, Edinburgh and London, 1880. 
This work was originally published in Germany, where it was so 
well received that it has induced the production of an English 
edition, the accompanying text being translated and edited by 
D. MAlpine, F.C.S., Lecturer on Botany at Edinburgh. It is 
precisely what its title states—namely, an “Atlas of Botany,” 
intended for use in schools or for illustrating lectures. The very 
clear manner in which the drawings have been prepared and 
coloured, together with their size, render them admirably adapted 
for either of those purposes. The object is to convey to the student 
of botany an accurate knowledge of the chief types of vegetable 
organisation, the phenomena of fertilisation, nutrition, and 
growth, the several organs and their functions, in fact everything 
of structural or physiological importance connected with the life 
of plants. The three parts we have received fairly indicate the scope 
of the work. They contain six plates each, size 3 feet by 2 feet, 
giving representations of portions of plants magnified from fifteen 
to eight thousand times, the following being the plants selected :— 
Salvia Sclarea, Volvox globator, Mucor Mucedo, Drosera rotundi- 
folia, Ophrys arachnites, Aspidium Filix-mas, Puccinia graminis, 
Lilium Martagon, Pinus Laricio, Schizomycetes, Bacterium an- 
thracis, Ulothrix zonata, prothallium of Aspidium Filix-mas, 
Cycas circinalis, and Polysiphonia subulata. Each part is accom¬ 
panied by a handbook fully explaining the plates, and forming a 
compendium of botanical instructions, containing all the latest 
information upon the subjects on which they treat, and excluding 
all doubtful matter. The following short extracts will suffice to 
indicate how this is accomplished :— 
“ Cosmarium botrytis belongs to the Desmidiaceae, a group of uni¬ 
cellular Algfe of symmetrical form. The cell appears as if in two 
halves, owing to a deep constriction in the middle. The protoplasm, 
coloured by chlorophyll, is usually interrupted in the middle, where 
a colourless nucleus is often to be seen. In each half-cell the bright 
green protoplasm is arranged in bands or discs, which bear a definite 
relation in number and arrangement to the larger globular or oval 
bodies—the starch-grains—which are single or in pairs, or even more in 
each half-cell. Besides the green protoplasm and the starch grains 
there is a colourless fluid in the cell, in which a large number of dark 
granules frequently occur with an oscillating movement, the so-called 
‘ Brownian ’ movement. The tolerably firm cell-wall of the Desmids 
is often covered with warty elevations, longitudinal striations, or 
wave-like prominences, and thin places or ‘ pores ’ also occur. All 
these markings on the cell-wall, which are characteristic for genera 
and species, often exhibit a definite arrangement in their distribution 
and a constancy in their number. Many of the Desmids which live 
isolated possess the power of slowly changing their place, while those 
species in which a number of individual cells are united into a fila¬ 
ment do not possess that power.” 
“Volvox globator, until quite recently considered by many natu¬ 
ralists as an animal, is the most complicated form belonging to the 
family of Algae known as Volvocineae. This family consists of plants 
made of a number of individual cells united into a rounded colony or 
ccenobium. Each individual cell is furnished with two vibratile cilia, 
which, acting in concert, give the whole a slow, stately, rolling 
motion in the water. Reproduction is of two kinds—non-sexual, in 
which individual cells of the colony repeatedly divide -while under¬ 
going rapid enlargement, and each portion gives rise to a young 
colony; or sexual, by the blending of spermatozoids and oospheres 
to form an oospore.” 
“ The common Brown Mould (Mucor Mucedo) is one of the com¬ 
monest of Moulds, and is found growing on the most various sub¬ 
stances. There is scarcely any decaying organic substance on which 
it may not be found. Let a piece of bread, for instance, be put in some 
damp place where it is protected from evaporation, and it is soon 
covered with a large crop of this Mould, aerial ascending branches 
of which developeso luxuriantly as to attain a height of 6 inches. It 
also occurs on bones kept in damp places and on horse droppings, 
where it grows very rapidly, since the spores introduced into the 
bod3 r along with the food are not only injured on their way through 
the digestive canal, but the warmth and moisture favour their growth. 
The Brown Mould grows in damp situations during the winter, even 
on papered walls, where it often spreads over the entire wall and 
rots the paper.” 
“ Puccinia graminis is remarkable for a complicated alternation of 
generations. To complete the cycle of its development there are no 
fewer than five kinds of reproductive cells, which, however, only 
develope and give rise to new generations when they are conveyed to 
quite distinct host plants. Within the last century farmers, whose 
entire crops were often attacked and partly destroyed by this Rust of 
Wheat, have recognised some sort of connection between the Barberry 
(Berberis vulgaris) and this rust disease ; and we are astonished to 
find that laws and orders had been issued as early as 1788 and later 
(1815), prohibiting the planting of the Barberry bush in the neigh¬ 
bourhood of corn fields, long before the fact had an incontestable 
scientific basis that there really exists the same connection between 
the Barberry and the Rust as between cause and effect. Modern 
microscopic investigation has succeeded in proving that connection. 
DeBary was the first to investigate the subject scientifically, and he 
has since been followed by a host of others.” 
“ Bacterium anthracis .—Of all the Schizomycetes which cause the 
putrefaction of organic substances, or are the propagators of infectious 
diseases, none has been better investigated than the living contagium 
of splenic fever. It was first discovered in the year 1849 by Pollender, 
and since then has been observed by various physicians and naturalists. 
It is owing to the joint and hazardous labours of these various inves¬ 
tigators, their numerous experiments and attempts at artificial culture 
in various infusions, that we are at present better informed concern¬ 
ing this Anthrax disease than about any other epidemic of men or 
animals, and possess a tolerably complete account of the whole history 
of the development of Anthrax. The researches upon this form may 
therefore be regarded as directly paving the way for, and as a typical 
example of, the numerous investigations still likely to be made in 
connection with contagious disease germs.” 
It is almost needless to add that the present edition is produced 
in a style suitable to the high reputation the publishers enjoy. It 
is stated that it will be completed in forty-two coloured plates 
with eighteen supplementary sheets. We recommend the work 
to the attention of all those employed in teaching botany. 
Thunbergia Harrisii.—I have been so greatly struck with 
the fine, softly shaded, peach-coloured, trumpet-shaped flowers 
persistently produced on the admirable winter-flowering climber 
