For several months we have had numerous inquiries respecting "Wardian Cases" waiting an answer. The following article, with illustrations, which we select from Mcintosh's Book of the Garden, is very complete, embracing a full and satisfactory description of all the most elegant and convenient contrivances for keeping house-plants that are known or in use in England, or on the Continent, where such things have been carried to great perfection. There are thousands of people shut up in cities who can have neither gardens nor green-houses, and yet can not wholly deny themselves the pleasure of cultivating a few plants ; and this can not be done in the dry atmosphere of living-rooms in a way to afford much pleasure.

The necessity for adopting window gardens, Wardian cases, or something equivalent, by those who are fond of having plants in their rooms, will, we think, be strengthened by the following remarks by Professor Lindley :

"'What, it may be asked, is there in the air of a sitting-room which plants are thus unable to support? Can any thing be purer than the atmosphere of an English drawing-room? Perhaps not; but it is this purity which in part inflicts the injury. Plants would thrive better if it were otherwise - but it is more especially its dryness. Let any one measure the moisture of a sitting-room and the open air. and he will see how great a difference prevails. We have,' says the learned Professor, * this moment tested it by Simmon's hygrometer: in the open air this instrument indicates 40°, in a sitting-room 60°. When plants are kept in a dry atmosphere they rapidly lose their water of vegetation; the sides of their pots are robbed at the same time; and it is impossible for plants to suck out of soil thus partially dried the moisture demanded for the sustenance of their exhausted foliage. Such a state of things is inseparable from a sitting-room. To render the latter congenial to plants, it would be uninhabitable by ourselves. The extent to which plants are injured in a common sitting-room is strikingly illustrated by the condition of cut flowers.

Let two clusters of fresh-gathered flowers be introduced into a sitting-room: place the one in the mouth of a narrow-necked jar of water, and arrange the other upon such a shallow pan of water as a deep dish will furnish. It will be found that the latter will be perfectly fresh days after the former have faded. The reason is, that in the narrow-necked jar the flowers have no access to water except through the ends of their shoots, and are surrounded with a very dry air; while, in the flat dish, they are able to absorb abundant water, because a large part of their surface is in contact with it, and are, moreover, surrounded by air incessantly moistened by the vapor which continually rises from the dish.

"Of this we may be sure, that darkness, dust, heat, want of ventilation, and all the other calamities to which plants in sitting-rooms are subject, are as nothing compared with the inevitable dryness of the air - which, indeed, acts injuriously not merely by exhausting plants of their water of vegetation, but by lowering the temperature of the pots in which they are grown, in consequence of the evaporation constantly taking place there. What makes the evil greater is, that the plants which are purchased for sitting-rooms are invariably brought into high condition by being grown in a damp atmosphere. They are transferred from the hands of skilful gardeners, armed with the most perfectly constructed forcing-houses, into the care of inexperienced amateurs, whose means of maintaining a plant in health are something considerably less than nothing.'

"Under the head of Window Gardening we shall include the various little contrivances of our Continental neighbors, who carry the cultivation of plants in rooms, on balconies, and in windows, to a much greater extent than has hitherto been done in this country, more especially in towns and cities, where the enjoyment of green-houses and conservatories is often denied them.

"N. Ward, Esq., an amateur cultivator, who lived many years in the heart of the city of London, carried the cultivation of plants, even rare ones, and those of difficult growth, to an amazing state of perfection, in small portable green-houses of elegant forms, and which have now become almost an indispensable article of furniture in every drawing-room. These are called Wardian cases, and are found to answer the purpose intended most completely, and are, perhaps, upon the whole, much better adapted for the end in view, as they are at the same time far more convenient and elegant, than the window-cases so frequently met with on the Continent - the former constituting an elegant article of furniture within the room, while the latter is attached to the outside of the window. They preserve the plants much longer in bloom or in a healthy state than the usual mode of setting them in stands or on tables, and at the same time afford a degree of agreeable enjoyment in their management.

"Mr. Ward has published a very interesting pamphlet on the growth of plants in such cases, which those interested in the matter should peruse. It contains, as Dr. Lindley has justly observed, 'all the information that can be given ; but it is in few hands, and everybody does not understand the principles on which his cases are constructed. It is imagined, by uninformed persons, that complete exclusion of air is the entire object which Mr. Ward sought to secure by his contrivance; but we need hardly tell the reader who knows any thing of the atmosphere, that such an effect can not be attained by a Ward's apparatus : the air finds its way into every place not hermetically sealed, and such contrivances as close glazing, puttying and so forth, can not exclude it What Mr. Ward sought to gain was uniformity of moisture and an exclusion of soot: and these he effectually secured. It is the drvness of the air that destroys plants in sitting-rooms and great towns, and not impurities in the gaseous constitution of the atmosphere, the importance of which has been singularly overrated. By enclosing plants in tightly-glazed cases, light is admitted, soot is excluded, and any desirable amount of moisture is securable.