Page:Transactions of the Linnean Society of London, Volume 6 (1802).djvu/92

This page has been proofread, but needs to be validated.
66
Mr. Howard's Account of a Microscopical Investigation

of a branch. To the naked eye it is a fine yellow powder. A few grains laid on the glass plate and viewed with the lens No. 4, some appear of an irregular angular shape, opake, except in one or two parts, where light passing presents the appearance of a perforation; others nearly spherical, the surface divided by depressed lines into a number of convex facets. The transparency of these is such, that they reflect the image of a small object held under them, as well as a drop of liquid. On repeating the examination, the former are found to come from the most mature anthers, and to differ from the latter only as a raisin does from a grape.

A clear drop of distilled water being put on. the glass, both kinds imbibe it with the avidity of a sponge; at the same time distending and spreading abroad in the water, but without any motion further than that which this expansion causes. When saturated with water they remain at the bottom, clear as the liquid itself, and all alike distended to a bulk many times greater than their original one in the dry state. They are now seen to the multilocular capsules, having septa in various directions within them, the union of which with the external membrane appears at the angles in the dry state, and at the depressed lines in the wet.

These capsules may be kept in the water for several days without any further perceptible change. When that is dried up they return to the opake state, and the same operation may be several times repeated on them.

In exhibiting this spectacle to some friends, pure water not being just at hand, a drop of brandy was substituted for it. This gave rise to a phenomenon equally curious and unexpected. The grains expand, as in water; but in the mean time they are put into rapid motion, each grain darting from side to side with the vivacity of a swarm of gnats in the air. As they approach to complete expansion the motion dies away, and one after another finks to the bottom.

By