RAISING FERNS FROM SPORES.
1, PAN; 2, BELL GLASS; 3, SMALL POTS AND LABELS.
This plan, of which I give a sketch, has been in use by myself for many years, and most successfully. I have at various times given it to growers, but still I hear of difficulties. Procure a good sized bell-glass and an earthenware pan without any holes for drainage. Prepare a number of small pots, all filled for sowing, place them inside the pan, and fit the glass over them, so that it takes all in easily. Take these filled small pots out of the pan, place them on the ground, and well water them with boiling water to destroy all animal and vegetable life, and allow them to get perfectly cold; use a fine rose. Then taking each small pot separately, sow the spores on the surface and label them; do this with the whole number, and then place them in the pan under the bell-glass. This had better be done in a room, so that nothing foreign can grow inside. Having arranged the pots and placed the glass over them, and which should fit down upon the pan with ease, take a clean sponge, and tearing it up pack the pieces round the outside of the glass, and touching the inner side of the pan all round. Water this with cold water, so that the sponge is saturated. Do this whenever required, and always use water that has been boiled. At the end of six weeks or so the prothallus will perhaps appear, certainly in a week or two more; perhaps from unforeseen circumstances not for three months. Slowly these will begin to show themselves as young ferns, and most interesting it is to watch the results. As the ferns are gradually increasing in size pass a small piece of slate under the edge of the bell-glass to admit air, and do this by very careful degrees, allowing more and more air to reach them. Never water overhead until the seedlings are acclimated and have perfect form as ferns, and even then water at the edges of the pots. In due time carefully prick out, and the task so interesting to watch is performed.—The Garden.
THE LIFE HISTORY OF VAUCHERIA.[1]
By A.H. BRECKENFELD.
Nearly a century ago, Vaucher, the celebrated Genevan botanist, described a fresh water filamentous alga which he named Ectosperma geminata, with a correctness that appears truly remarkable when the imperfect means of observation at his command are taken into consideration. His pupil, De Candolle, who afterward became so eminent a worker in the same field, when preparing his "Flora of France," in 1805, proposed the name of Vaucheria for the genus, in commemoration of the meritorious work of its first investigator. On March 12, 1826, Unger made the first recorded observation of the formation and liberation of the terminal or non-sexual spores of this plant. Hassall, the able English botanist, made it the subject of extended study while preparing his fine work entitled "A History of the British Fresh Water Algæ," published in 1845. He has given us a very graphic description of the phenomenon first observed by Unger. In 1856 Pringsheim described the true sexual propagation by oospores, with such minuteness and accuracy that our knowledge of the plant can scarcely be said to have essentially increased since that time.
GROWTH OF THE ALGA, VAUCHERIA, UNDER THE MICROSCOPE.
Vaucheria has two or three rather doubtful marine species assigned to it by Harvey, but the fresh water forms are by far the more numerous, and it is to some of these I would call your attention for a few moments this evening. The plant grows in densely interwoven tufts, these being of a vivid green color, while the plant is in the actively vegetative condition, changing to a duller tint as it advances to maturity. Its habitat (with the exceptions above noted) is in freshwater—usually in ditches or slowly running streams. I have found it at pretty much all seasons of the year, in the stretch of boggy ground in the Presidio, bordering the road to Fort Point. The filaments attain a length of several inches when fully developed, and are of an average diameter of 1/250 (0.004) inch. They branch but sparingly, or not at all, and are characterized by consisting of a single long tube or cell, not divided by septa, as in the case of the great majority of the filamentous algæ. These tubular filaments are composed of a nearly transparent cellulose wall, including an inner layer thickly studded with bright green granules of chlorophyl. This inner layer is ordinarily not noticeable, but it retracts from the outer envelope when subjected to the action of certain reagents, or when immersed in a fluid differing in density from water, and it then becomes distinctly visible, as may be seen in the engraving (Fig. 1). The plant grows rapidly and is endowed with much vitality, for it resists changes of temperature to a remarkable degree. Vaucheria affords a choice hunting ground to the microscopist, for its tangled masses are the home of numberless infusoria, rotifers, and the minuter crustacea, while the filaments more advanced in age are usually thickly incrusted with diatoms. Here, too, is a favorite haunt of the beautiful zoophytes, Hydra vividis and H. vulgaris, whose delicate tentacles may be seen gracefully waving in nearly every gathering.