Page:Hardwicke's Science-Gossip - Volume 1.pdf/221

is borne at the tips of the fronds; and this species is recommended as the best for microscopical examination. Professor Harvey advises that fresh specimens should be collected in winter or early spring, and, being removed from the water, should be left till partially dry. As the surface dries there will exude from the pores of the receptacle drops of a thick orange-coloured fluid, which, on being placed under a microscope and moistened with salt water, will be found to be composed of innumerable cellules, from which will issue troops of these atoms, that are no sooner liberated than they commence those singular motions which the naturalist finds it so difficult to reconcile with vegetable life.

But the species best known and most highly appreciated by juveniles, though not the most

common, is the Knotted Wrack, or "Crackers" (Fucus nodosus). The air-vessels are very large, and on being thrown into the fire burst with a loud report; herein lies the cause of the popularity alluded to. No distinct midrib runs up the fronds, which are narrow and thickened. The receptacles which bear the fructification are not terminal, as in the former species, but borne on stalks or pedicels issuing from either side of the fronds. In the present species the spores separate into four, and in the Serrated Wrack into eight parts or sporules. A parasitic sea-weed often grows upon and nearly covers the Knotted Wrack.

There is also a much smaller kind of wrack (Fucus canaliculatus), the fronds of which are only a few inches in length. The fructification is borne at the tips of the fronds, and the spores separate into two sporules. Two other species. belonging to the

same genus are found on our shores, but are less common.

Apropos of the name of "wrack"—which is commonly given to these plants of the sea,—in the Channel Islands it is vraic, and this is derived from the French varec, signifying sea-weed. So that in using the word "wrack" we are employing a corruption of the French word for "sea-weed."

If this brief notice of some of the common objects of the shore should lead any to examine for themselves what they have never observed with any interest heretofore, and to gather instruction from what they have almost despised, our design will be consummated. "There is nothing in nature so common, but we may always learn something from it, if we will but take the trouble to learn."

Cultivation of Butterworts.—Pinguicula vulgaris, and, indeed, any of the other species, may be easily treated in a state of cultivation, by attention to the following method, successfully adopted in our North Wales Botanic Garden. Collect the plants while in a state of hybernation, any time between November and March; at that period of the year they resemble bulbs, and can be picked off the surface of the bogs and moors in abundance. Fill a saucer with finely broken pieces of peat, and as much water as can be absorbed by the peat, and then place the bulbs simply upon its surface, without burying them in, or beneath it; just steady them and keep them supplied with moisture, and they will soon strike their fibres downwards and spread their leaves upon the surface, and make a beautiful appearance during the season.—W. P. in Botanists' Chronicle.