Dr. Stephen H. Ward delivered a lecture on this occasion, on "Wardian Cases," of which the following is an abridged report Dr. Ward began by explaining the circumstances which had led his father to adopt air-tight cases for the accommodation of his London window plants. He had placed a chrysalis in a bottle, with a little damp earth, in order to watch its progress towards transformation into a moth; a Fern and a Grass began to vegetate, and, to his surprise, continued to show a healthy appearance, the former on its more perfect development proving one of his favorites, which he had often failed in rearing under ordinary circumstances. On investigating and questioning himself on these appearances, the answers readily presented themselves, inasmuch as all the requirements of nature were contained within the bottle - air, light, and moisture. Many persons had fidlen into the error that Ward's cases were, or ought to be, hermetically sealed; on the contrary, a change of air is frequently necessary; this will imperceptibly occur in the closest made cases, or they would inevitably burst The trough to contain the earth may be made of any materials - earthenware or wood pitched inside; but the best are cine Of all, by far the best were stated to be bell-glasses, which are also admirably adapted for cut flowers, which are long preserved in them, as in the case of a Camellia, which, on one occasion, had retained its beauty for nearly a month.

To size there are no limits - from an ounce phial even to the Crystal Palace itself. The decay of a healthy plant on transmission to a room in town is effected by the .variety of noxious gases, evaporation from dryness of air, frequent and sudden alteration of current vided against by tlie glass case, while the moisture which was raised became condensed on the sides of the glass on occasions of change m the external te\mperature, accumulating and ciescend-ing to the earth, at the bottom becoming more perfectly aerated, and in a state better adapted for stimulating and nourishing the plant. Sc complete is the routine in such a little world, in itself independent of external circumstances, that the old bottle sealed up 19.years since is green with vegetation, though the deposits of Conferva on the inner surface materially disfigure its appearance. This bottle has had no fresh moisture since first closed. The advantages, besides those of mere ornament, were stated to be great - to the poor man in hospitals, treatment of the insane, transportations of plants from one country to another, duration of flowering, to all ranks confined in cities and sick rooms, they were stated to be a blessing.

At St. Thomas' Hospital a subscription has been set on foot to provide cases, one of which was exhibited, most elegant in form, and in these the patients found a fruitful source of gratification. One of the advantages belonging to cases of this kind was the facility of transmitting plants from one country to another. Mr. Fortune has sent to this country 250 specimens, out of which 215 have arrived in health. Mr. Ward successfully forwarded to Sydney a variety of English plants in a case that was five months on the passage; on its arrival there the Primrose was just blossoming; and this case subsequently returned to England with a collection of Australian plants. The carbonization of the atmosphere by animal respiration, and the restoration of oxygen by vegetation, is a well known fact, and upon this Mr. WARD claims the merit of suggestions as to sanitary buildings in which vegetation would form a conspicuous feature. In connexion with the restorative nature of the process of vegetation, a taper was put under a bell-glass containing a Rose and other flowers, and was extinguished in ten minutes. But after exposing the glass to the sun for about three hours, the taper could be again kept alight for the same period as before.

In the same manner vegetation in water would be found to restore the oxygen, and in consequence it was possible to keep fish in air-tight cases, when vegetation was allowed to accompany them. To Mr. Ward was due the credit of having first introduced a vivarium into a closely glazed case in 1841, and for having depended for the renovation Of the air necessary for the gold and silver fish contained therein upon the purifying action of associated plants, such as Pontederia crassipes, Pisiia stratiotes, Valisneria spiralis. Mr. Bowerbank took the hint from Mr. Ward, and established a little vivarium in a large glass jar - stickle-backs, minnows, and fresh water snails, and with plants of Valisneria, and covered the mouth of the jar with glass, so as to make it a closed case. Snails, for the purpose of removing the Conferva? that cover the leaves of Valisneria and other aquatics, were first recommended -in a note in the number of the "Microscopical Journal" for September, 1841. It was, however, stated that ago long ago as 1788, LedebMullEr had published, in his "Microscopical Recreations." a figure of an open-mouthed bottle containing fresh-water zoophytes, associated with Duckweed, Chara, and other plants.

Mrs. Tutnwk first introduced marine vivaria into London; having brought some living Madrepores up to town in 1846, from Torquay, she placed them in two glass tanks, and at first effected aeration of the water by having it daily taken out and poured in gradually from a height, occasionally sending for fresh sea-water and thoroughly renewing it; after a year, or two her Madrepores seemed to flag, and then she proerred some pieces of rock and shell with living sea-weeds attached, and subsequently depended upon the counterbalancing action of these, Dr. Ward decidedly entertains sanguine hopes that success will ultimately attend the adaptation of the principles in extension to the maintenance or restoration of health to the human frame, although he admits that difficulties would present themselves In the attempt to realize such adaptation. - Gardeners' Chronicle.