ZOOLOGICAL GARDENS.
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.