Since our last visit, many of the tenants have begun to _hybernate_, and
tasteful erections have been made for their winter quarters in all parts
of the gardens. Several others are in progress, and a semi-circular
aviary for British birds is already built. The _season_ is far advanced,
and there have been but few _arrivals_ of late. The _emus'_ grounds have
been enclosed with elegant iron-work, and several removals or _changes_
have taken place. Some of the animals are much affected by the cold
weather. Thus, the monkeys have left their houses on poles, and retired
to enclosed cages, where they nestle in groups of threes and fours, and
amuse themselves by teazing the least of their company; for here, as
elsewhere, the weakest goes to the wall. Three fine wolves, previously
shut up in a small den, now enjoy a large cage, where they appear much
invigorated by the bracing season. Here and there a little animal lies
curled up in the corner of his cage, in a state of torpidity. Among the
birds, the macaws were holding an in-door council in their robes of
state; whilst one fine fellow, in blue coat and yellow waistcoat,
perched himself outside the aviary, and by his cries, proved that fine
colours were not weather-proof. The snowy plumage of the storks was
"tempered to the wind;" but they reminded us of their original
abode--the wilderness. The eagles and vultures in the circular aviary
sat on their perches, looking melancholy and disconsolate, but well
protected from cold. The kangaroos have removed into their new house,
and their park has been relaid, although they still look unsettled. A
very pretty beaver-house has been built of mimic rocks.
Among the _introductions_, or new faces, we noticed a pair of fine
mastiffs from Cuba, and two Thibet watch-dogs. One of the latter stood
shivering in the cold, with bleared eyes, and crying "like a lubberly
postmaster's boy." The three bears exhibited as much good-breeding as
the visiters encouraged,--climbing to the top of the pole when there was
any thing to climb after, and an Admiralty expedition could do no more.
_Poisoning of Vegetables_.
Several very curious experiments on the poisoning of vegetables, have
recently been made by M. Marcet, of Geneva.--His experiments on arsenic,
which is well known to every one as a deadly poison to animals, were
thus conducted. A vessel containing two or three bean plants, each of
five or six leaves, was watered with two ounces of water, containing
twelve grains of oxide of arsenic in solution. At the end of from
twenty-four to thirty-six hours, the plants had faded, the leaves
drooped, and had even begun to turn yellow; the roots remained fresh,
and appeared to be living. Attempts to restore the plants after twelve
or eighteen hours, by abundant watering, failed to recover them. The
leaves and stem of the dead plant gave, upon chemical examination,
traces of arsenic. A branch of a rose-tree, including a flower, was
gathered just as the rose began to blow; the stem was put into a vessel,
containing a solution of six grains of oxide of arsenic in an ounce of
water. The flower and leaves soon showed symptoms of disease, and on the
fifth day the whole branch was withered and dead, though only one-fifth
of a grain of arsenic had been absorbed. Similar stems, placed in pure
water, had, after five days, the roses fully expanded, and the leaves
fresh and green.
On June 1st, a slit of one inch and a half in length was made in the
stem of a lilac tree, the branch being about an inch in diameter. The
slit extended to the pith. Fifteen or twenty grains of moistened arsenic
were introduced, the cut was closed, and the stem retained in its
original position by osier ties. On the 8th, the leaves began to roll up
at the extremity; on the 28th, the branches were dry, and, in the second
week of July, the whole of the stem was dry, and the tree itself dead.
In about fifteen days after the first, a tree, which joined the former a
little above the earth, shared the same fate, in consequence of its
connexion with that into which the poison had been introduced. Other
trees similarly cut, but without having been poisoned, suffered no kind
of injury.
M. Marcet's experiments upon vegetable poisons are no less interesting,
and still more wonderful, as indicating a degree of irritability in
plants somewhat similar to that which depends on the nervous system in
animals. After having ascertained that the bean plants could exist in a
healthy state for five or six days, if immersed in the same quantity of
spring water, he tried them with five or six grains of opium dissolved
in an ounce of water, the consequence of which was, that in the evening
the leaves had dropped, and, by the middle of next day, they were dead
beyond recovery. Other vegetable poisons of the narcotic class produced
a similar effect. Hemlock was equally fatal, and six grains of dry
powdered foxglove, in an ounce of water, began to operate, by wrinkling
some of the leaves of the bean in a few moments, which it completely
killed in twenty-four hours. Oxalic acid or salt of sorrel, though found
in common and wood sorrel, and a great many plants, proved a very fatal
poison to others. The absorption of one-tenth of a grain, killed a rose
branch and flower in forty--eight hours.--
_Quar. Jour. of Agriculture._
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