OF GARDENING AS A SCIENCE. 
203 
grotto. The external surface of the lights is quite disfigured with the soot which 
abounds in the impure atmosphere of Wellclose-square : yet in this gloomy and 
extremely damp erection, Ferns of all climates flourish in verdant health ; and not 
ferns only, but Thunhergia^ Begonia^ Fuchsias^ and other plants, which are the 
ornaments of our stoves and greenhouses. In the glass cases no air can enter but 
what passes through the mould ; and yet, if our memory deceive us not, some Or- 
chidacese and tropical plants thrive and even blossom, although neither air has been 
admitted for seven years, nor any water given for more than five months. We will 
now refer to the article in question. 
" I was accidentally led, about four or five years ago, to make some experiments 
on the growth of ferns, &c. in closely-glazed vessels, from the following circum- 
stance : — I had buried the chrysalis of a Sphinx in some moist mould in a large 
bottle, covered with a lid. The insect attained its perfect form in about a month, 
when I observed one or two minute specks of vegetation upon the surface of the 
mould. Curious to observe the development of plants in so confined a situation, I 
placed the bottle outside one of my windows with a northern aspect : the plants 
proved to be one of Poa annua, and one of Nephrodium {Asplenium, Swz.) filixmas. 
In tliis situation they lived for more than three years, during which time no fresh 
water was given to them, nor was the lid removed. The fern produced four or five 
new fronds every year ; and the Poa flowered in the second year, but did not ripen 
its seeds. Both plants ultimately perished from the admission of rain-water, in con- 
sequence of the rusting of the lid. I have repeated this experiment with uniform 
success upon more than sixty species of fern," (these are enumerated,) " and also 
several other plants which delight in moisture, as Oxalis acetosella. Anemone 
nemorosa, Dentaria hulhifera^ &c. &c. 
" The ferns, &c. may be placed in boxes of any size or shape, furnished with 
glazed sides and a glazed lid. The bottom of the box should be filled with nearly 
equal portions of bog-moss, vegetable mould, and sand ; and the ferns, after planting, 
should be most copiously watered, and the superfluous water allowed to drain off 
through a plug-hole in the bottom of the box : the plug is then to be put in tight, 
the glazed lid applied, and no farther care is requisite than that of keeping the box 
in the light. In this way plants will grow for years without any fresh supply of 
water. The numerous experiments I have already made have, I think, established one 
important fact — that the air of London, when freed from adventitious matter, is as 
fitted to support vegetable life as the air of the country. — N. B.Ward. March 1834." 
We may now safely inquire, of what use is air to vegetation ? and from com- 
parison of facts, are inclined to indulge the converse of the received opinion, and to 
presume, that plants are the instrument adapted by nature to the purification of air. 
Air, that is, the mixture of oxygen and nitrogen, doubtless promotes the proli- 
ficacy and maturation of plants : it checks luxuriant growth, favours the development 
of the floral organs, promotes evaporation, and carries off moisture with rapidity ; 
but if we seek in it the supply of nutrimental matter, we shall possibly be disap- 
