CULTIVATION. 
369 
In the latter case, sometimes their own weight makes 
them fall lower than is convenient ; it therefore 
becomes necessary to support them by inconspicuous 
stakes. Care must, however, be taken not to raise the 
fronds above their natural position, and to avoid making 
them have a stiff formal appearance. 
In “ Theories of Horticulture,” it is said that 
abundance of light and a free circulation of air are 
indispensable for the cultivation of plants under glass, 
lu my long experience, I have found, as a rule an 
abundance of light and a too free circulation of ail- 
prejudicial to the good cultivation of plants in general. 
With regard to Ferns, they love a quiet, dull atmo- 
sphere ; the light afforded by a roof glazed with the 
ordinary transparent glass, admits fully double the 
amount of light necessary during eight months of the 
year. Sufficient means are, however, necessary for 
admitting air, in order to keep down the temperature 
in summer ; but care must be observed in admitting 
it ; if not, the increased ventilation in lowering the 
temperature will cause a rapid dispersion of the essen- 
tial moist atmosphere at a time when most required. 
Shading must then be resorted to, this being the chief 
purpose which it serves, besides protecting the plant’s 
foliage from the too powerful rays of the sun. It may 
•consist of canvas blinds on rollers; two moderately 
thick ones are much better than one very thick, espe- 
cially when Trichomanes and Hymenophyllum are 
grown ; one should be permanent during the height of 
the summer, the other to roll over it on occasions of full 
sunshine. Although canvas is here spoken of as best 
for shading, and is extensively used, still it is trouble- 
some, and in the end expensive, which makes it de- 
