THE COTTAGE GARDENER AND COUNTRY GENTLEMAN, September 6, 1859. 
339 
is only because it is constantly exposed to the influence of light 
and air, and to the contact of such bodies as float in the atmo¬ 
sphere ; but it is not to be regarded as constituting a distinct 
organ or membrane, or as exhibiting any proof of its being 
analogous to the epidermis of animals.— (Trait. cl'Anat. el de 
Phys. Veg., i. 87.) 
Yet, if it is true that the epidermis i3 nothing more than the 
pellicle formed on the external surface of the parenchyma, 
indurated by the action of the air, then it will follow that an 
epidermis can never be completely formed till such time as it has 
been exposed to that action. But it is known that the epidermis 
exists in a state of complete perfection in cases where it could 
not possibly be affected by the external air. If you take a Rose¬ 
bud, or bud of any other flower, before it expands, and strip it of 
its external covering, you will find that the petals and other en¬ 
closed parts of the fructification are as completely furnished with 
their epidermis as any other parts of the plant, and yet they have 
never been exposed to the action of the air. The same may 
be said of the epidermis of the seed while yet in the seed-vessel, 
or of the root, or of the Paper Birch, which still continues to 
form and to detach itself, even though defended from the action 
of the air by the exterior layers.— ( Keith's Lexicon.) 
Liebig has gone a step further even than Mirbel. lie obtained 
the following analyses 
Ashes of Wood 
Ashes of the Burk 
of the Fir 
of the Fir 
Hertwig. 
Hertwig. 
1000 wood gave 3.28 ashes. 
1000 bark gave 17.85 ashes 
Soluble Salts 1S.72. 
Carbonate of soda 
. 7.42 
Carbonate of potash 
. 11.30 
Soluble salts 2.95 
Chloride of sodium . 
■ Traces. 
Sulphate of potash 
Insoluble Salts. 
Insoluble Salts 97 
Carbonate of lime 
. 50.94 
64.98 
Magnesia 
. 5.60 
0.93 
Phosphate of lime 
. 3.43 
5.03 
„ magnesia . 
. 2.90 
4.18 
manganese 
. Traces. 
„ peroxide of iron 1.04 
1.04 
„ alumina . 
. 175 
2.42 
Silica .... 
. 13.37 
17.28 
Loss .... 
. 2.26 
1.79 
100.00 
100.00 
Because the wood and the bark “ differ essentially from each 
other, both in their composition and characters,” Liebig con¬ 
cludes that “ the inorganic ingredients of the bark are obviously 
inorganic substances, expelled by the living organism,” and “ are 
in so far true excrements, that they arise from living plants and 
play no further part hi their vital functions ; they may even be 
removed from them without thereby endangering their existence. 
It is known that certain trees throw oil' annually them barks: 
this circumstance, viewed in its proper light, shows that, during 
the formation of certain products formed by the vital processes, 
materials arise which are incapable of experiencing a further 
change.” 
This conclusion is certainly illogical; for, from similar premises 
it might be concluded that the shell of the lobster and of other 
Crustacea) are “ true excrements; ” and, moreover, it is a con¬ 
clusion refuted by all experiments upon its functions, and by 
the fact, that to denude a plant of its epidermis, and to keep 
it so denuded, is a treatment certainly followed by disease and 
decay.—J. 
(To le continued.) 
NEW BOOKS. 
Celestial Objects.* —This is just the kind of book which 
should be found in the literature of every scienco. It has for 
its object directions how to use a common telescope, and point¬ 
ing out what advantageously may be looked for in the heavens. 
It is a book of recreations in astronomy. The author has ex¬ 
ceedingly well executed what he proposed to accomplish, as will 
be appreciated from the following extract, which we select for 
its brevity; but there are many other planets, the moon espe- 
* Celestial Objects for Common Telescopes. By the Rev. T. W. Webb, 
M.A., &c. London : Longman, Green, Longman, and Roberts. 
daily, about which the objects he points out for a telescope are 
much more interesting. 
“ MERCURY. 
“ This planet, though at times readily visible to the naked 
eye, is but seldom seen from its nearness to the sun ; and often 
lies too near the horizon for the telescope. A well adjusted 
equatoreal-stand will find it by day, but its small diameter of 
less than 3000 miles subtends ’as a mean not more than 0" or 
7"; and ordinary observers will not see much where professed 
astronomers have usually found little. But as these pages 
may possibly fall into the hands of some whose advantages or 
enterprise may lead them to attack a neglected object, the fol¬ 
lowing points may be specified :— 
“ 1. The Phases. These will he easily seen, and are only re¬ 
markable because the breadth of the enlightened part has been 
sometimes found less than it should be from calculation. 
Schroter noticed this, and it is confirmed by Beer and Miidler; 
but their explanation of a dense atmosphere making the ter¬ 
minator, or boundary of light and darkness, faint, is inadequate, 
as their observation was before sunrise, when the dullest part 
of the disc would still be very luminous. 
“2. The Mountains. At the close of the last and beginning 
of this century, Schroter, of Lilientlial, in Hanover, a most 
diligent observer, and bis assistant Harding, obtained what 
they deemed sufficient evidence of a mountainous surface in 
the occasional blunting of the S. horn, some minute pro¬ 
jections on its outer edge, and an irregular curve of the ter¬ 
minator; they gave the inferred elevations a height of nearly 
eleven miles perpendicular. 
“ 3. The Atmosphere. The decrease of light towards the ter¬ 
minator, and the occasional presence of dark streaks and spots, 
indicated to the same astronomers a vaporous envelope, where 
they thought they even saw traces of the action of winds. ! 
From a combination of these appearances they deduced a 
rotation in 24h. 0m. 53s. on an axis inclined about 70° to its j 
ecliptic. But further observations are needed. In De La Rue’s j 
magnificent Newtonian, ten feet focus and thirteen inches 
aperture, constructed by himself, the planet has a rosy tinge. 
“ Transits of Mercury are comparatively frequent.; they will 
be visible in Europe in 1801, 1808,1878, and 1894. The planet | 
breaks in upon thesun as a dark notch, sometimes preceded,itis j 
said, by a penumbral shade ; but the earliest impression will be 
missed, unless the exact point of the sun’s limb is known, and 
kept central in the field. As it advances, the part of Mercury 
not yet entered on the sun may be rendered visible by being 
projected upon the * corona ’ or illuminated atmosphere, which 
is so conspicuous in total solar eclipses, and has been known to 
relieve dark bodies in front of it, such as Mercury, Venus, or 
even a portion of the moon. On finally entering the sun, or 
beginning to leave it* the planet has been seen lengthened to¬ 
wards the limb; probably from irradiation, which often enlarges 
luminous images at the expense of contiguous dark spaces. 
Fully on the sun, Mercury appears intensely black; some astro¬ 
nomers have given it a slight dusky border, others a narrow 
luminous ring; both, probably, deceptions from the violent 
contrast and the fatigue of the eye, especially as others have 
seen neither. But whatever is seen should always be recorded. 
A stranger appearance is better attested—that of a whitish or grey 
spot on the dark planet, seen by Wurzelbauer, 1697, Schroter, 
Harding, and Kohler, 1799; Fritsch, and others, 1802; Moll 
and his assistants, 1832 (when Harding clearly distinguished 
two spots, and Gruithuisen suspected one): and recognised in 
England and America, 1848. No terrestrial analogy will explain 
a luminosity thus visible close to the splendour of the sun ; 
but the testimony seems irresistable. Schroter and Harding 
ascribed to these spots amotion corresponding with the rotation 
which they subsequently inferred from other indications.”* 
THE GISHURST COMPOUND. 
In The Cottage Gardener of August 23rd, you answer a i 
correspondent’s query whether Gishurst Compound contains 
arsenic. As others of your readers may have had similar doubts, 
perhaps you will allow me to answer them. Gishurst Compound 
lias never contained arsenic, nor any other ingredient poisonous or 
injurious, except to small insects and fungi. Its most active ^ 
• A similar phenomenon was observed on Venus in the transit of 1761 | 
(Append. a<l Ephem. Astron. 1766, 62), for the explanation of which, in ! 
the additional light derived from the transits of Mercury, the Abbot Hell's ■ 
theory of optical illusion seems quite insufficient. 
