silk-worm is 1,900 feet, it follows that the produce of one silk-worm is
equal to that of 6.3 spiders. Now, as on an average it takes about 3,500
silk-worms to produce a pound of silk, it would take about 22,000
spiders to produce an equal quantity. Besides, spiders are not so easily
confined as silk-worms, and whenever two come in contact, a battle
ensues, which ends in the destruction of the weaker one. Spiders kept
for silk must, therefore, be each in separate dens or cells; and the
apparatus contrived by Mr. Rolt for this purpose, although very
ingenious and well adapted to carry on a course of experiments with a
hundred or two, would manifestly be wholly inapplicable to any purpose
of commercial utility. Mr Rolt has, however, made some interesting
additions to the history of the garden spider, and has obtained the silk
in its natural state, exhibiting all its peculiar lustre; his method,
likewise, of winding the silk directly from the animal is, to say the
least of it, effectual and ingenious."

It should be added that "the Society are of opinion that it will never
be possible to employ spiders' silk, beautiful as it is, in any
profitable manufacture; but have thought proper to confer a reward on
this gentleman for his communication, as forming an interesting addition
to the natural history of the spider."

_Medicinal Employment of Holly Leaves._

Dr. Rousseau has obtained from the Medico-Botanical Society of London
its silver Medal, for an essay on the effects of holly leaves in fever:
he has cured several intermittent fevers by the remedy, whose alkali he
calls Ilicine.--_Gazette of Health._

_Tobacco no security against Cholera._