OF PLANTS AND PLANT-HOUSES. 
207 
t 
The disciples of the theory promulgated by Mr. Ward, in whose air-tight glass 
c; 3S plants such as Cacti, Orchids, Ferns, and other Cryptogams, managed to drag 
0 an enfeebled existence for many months, ran away with the idea some years 
b k, that because these plants lived, other plants must grow, and consequently 
v tilation became a very secondary consideration among scientific men ; indeed, we 
r dlect a range of houses, the top sashes of which were all screwed down, and the 
milt was, the black Hambro’ Grapes became red ones in succeeding years, and the 
g» dener lost his situation. To these houses air was admitted by holes cut midway 
t ween the glass and the footpath of the house in the back wall ; but these holes 
\ never reopened, except to lower the temperature of the house. Horticultural 
ahitects, who too frequently know nothing of practical gardening, soon took up the 
1 a, because it was fashionable ; and hence it would be easy to point to iron-roofed 
Uses built about that time, which were so badly ventilated, as to render it 
i possible, without shading in sunny weather, to prevent the plants being 
firched to death. This was one of the reasons why metallic-roofed houses became 
f unpopular, and were so much dreaded by professional men. 
We have always laid it down as a rule, that plant and forcing-houses should 
] per be closed during either night or day except in the most severe weather, but 
| it “from night to morn, from mom to dewy eve,” there should be a constant and 
Jrpetual interchange of the external and internal atmospheres. While, however, 
•ji would do everything in our power to secure this interchange, there are one or two 
mgs which must be carefully guarded against. We all know how very injurious it 
to the animal frame to be placed in a current or draught, and that a current of 
■ admitted through a broken window will lay the foundation of diseases which will 
ickly gather a strong man to his fathers. Scarcely less injurious are currents of 
:: to plants, no matter whether they be warm or cold ; and there are certain green- 
use plants — as, for illustration, Boronia serrulata and pinnata, Crowea saligna, 
e whole tribe of Gompholobiums, and many other Swan River and New Holland 
ants — which, if placed in a current, will not only refuse to grow, but will positively 
je. Even Heaths hate a current such as is admitted by the small opening of a 
sh, but they delight in a free circulation of air, admitted in a volume, so as to act 
)on the whole plant at the same time. No greater proof can be given of the inju- 
ius tendency of currents of air to plants, than the fact, that a current of frosty air 
Imitted through a broken square will kill a plant in a greenhouse, the temperature 
’ which shall never be below the freezing point, while the same plant, though frozen 
lite hard, but protected from a current, would be uninjured. This fact we proved 
weral times during the last severe winter, and so satisfactory was it to us, that 
hile we admit all the air we can to our plant-houses, we always take care to guard 
gainst strong currents. 
From the preceding remarks it will be seen that the ventilation of plant-houses 
an operation which requires careful management, and is a point in cultivation 
hich it is necessary should be well studied. In congenial weather, of course, air 
