Page:Transactions of the Linnean Society of London, Volume 6 (1802).djvu/94

68 If a pistil be separated from the expanded flower with grains of pollen adhering to it, the latter will be found already expanded to a spheroid. Cover the whole with a drop of spirit on the glass, the pistil is not affected in any way, but some of the grains quit it and revolve on their axes. When these are exhausted, the addition of more spirit excites others: after a few minutes, some of those first excited begin to put out a small thread, which gradually elongating, the grain diminishes in proportion, until it is entirely drawn out into a vermicular fibre, which again is presently dissipated into particles too minute to be seen in the now opake medium. The liquor from the tube of the pistil, and a solution of sugar in water, were also found to produce this evolution in very mature grains from the anther. It also sometimes takes place in the twinkling of an eye, so as to be scarcely traced in some few grains out of a number put into spirit at once. Those which have been some time in contact with the pistil are always most: sluggish in their evolution.

5. Carex acuta. Anthers oblong, crumbling. Pollen angular, opake, with apparent perforations. It dilates in spirit and remains stationary, but ejects numerous minute particles in rapid succession from its surface. When it has become transparent it appears as if filled with seeds.

The preceding may serve for examples of these phænomena; but there was not one among the various species I examined, which did not exhibit them in a greater or less degree. Yet various other parts of the flower, immersed in spirit under the microscope, did not betray the smallest vestige of them.

The proper spirit for this purpose seems to be a mixture of one part pure spirit of wine with two of water. A stronger spirit, or even spirit of wine alone, may sometimes be required when we operate upon a pollen which has, by any means, became previously saturated