As to the pleasure derived from the cultivation of plants in rooms, - though very few are capable of resisting the poisonous action of the products of the combustion of gas, - there can be no difference of opinion, but many persona labour under the delusion that their presence is injurious to health. It is true that certain powerful perfumes may induce headaches, but the notion with regard to plants in general is based on a misconception as to the nature of the nutritive process incorrectly called their respiration, which is assumed to be similar to that of animals, whereas it is in fact precisely the reverse. Animals absorb oxygen from the air, giving out in exchange an equal volume of carbonic acid, which plants aborb under the influence of light, converting it into starch and woody fibre or cellular tissue. They thus preserve the purity of the air by removing the poisonous gas evolved by animals and the combustion of hydrocarbons, and maintain the equilibrium of nature. This process is suspended in the dark, but the amount of oxygen they take up even then in true respiration is insignificant, and when one considers that far the greater part of the structure of a plant is built up of the carbon derived from the carbonic acid in the air, one cannot but feel that their power as purifiers of the atmosphere, which otherwise would in time become unfit for the maintenance of animal life, must be enormous.

There are, however, very few plants that can be grown in rooms lighted by gas; aspidistras, draeanas. and some palms, robust ferns, and cactuses, are the least susceptible. The compounds of sulphur, among the products of the combustion of coal-gas. are most fatal to vegetable life, so that in this respect the smokeless incandescent gas-light possesses no advantage.1 Oil and candles, being free from sulphur, are harmless, and electric light, like that of day, is actually beneficial. Where gas is used, the difficulty may be overcome by window-eases, the inner sashes being closed so soon as the gas is lighted. Such cases fitted to window-, the outlook from which is not pleasant, may be made extremely ornamental, and if the aspect be northerly or the sunshine shut off by neighbouring buildings, they may be filled with ferns, palms, and other plants which prefer the shade.

Hermetically-sealed glass cases, or simple bell-glasses closely fitting the pan of earth beneath, and filled with delicate ferns, selaginellas, etc, constitute most elegant table decorations. In these "Wardian" cases, plants will thrive for years without any attention whatever, provided only they have as much light as the particular kinds require.

The use of foliage, interspersed with a few flowering plants, need by no means be limited to rooms and windows. A skilful florist can convert an area into a fernery and moss-clad grotto, or a backyard into a winter-garden. In these positions the choice of plants, and especially of flowers, is restricted to such as love the shade, but the possibilities of roofs are vast. On the warm sunny "leads" of a wing or addition, sheltered by the wall of the main building, a luxurious conservatory or orchid-house may be erected, approached by glass doors and curtain- from a passage or landing; on the shadier side may be a fernery, while the roof of the house itself, if the style permit of its being fiat, would afford an excellent position for a large conservatory and a terrace, with seats and boxes of plants, providing a garden where there would otherwise be none, and where a purer air could be enjoyed than in the streets or the confined gardens of houses in towns. In this respect we might well take a lesson from the peoples of Eastern and tropical countries, among whom the house-tops are the favourite evening resort of the family.

1 Except that, in a given time, and for the same amount of light, it burns less gas than an ordinary burner, and consequently may be expected to have a less rapid affect on planta. - Ed.

The Principles And Practice Of Modern House Construction