368 
FERNS : BRITISH AND FOREIGN. 
the purpose of giving consequence and dignity to the 
house, thus laying the foundation for conditions un- 
favourable to plants. The shelves orbenches may consist 
of dark-coloured porous stone or rough slate, with an 
edging of smooth slate two inches deep, so as to form a 
shallow trough, which should be filled with dark- 
coloured sand or fine-sifted coal-ashes, the whole 
pressed down, so as to form a firm smooth surface, on 
which the pots are to be arranged. By this means a 
degree of moisture will be retained more congenial to 
the plants than when standing on stone or slate. An 
edging of about three inches of Selaginella hortensis or 
S. denticulata gives a neat appearance, and if allowed 
to run between the pots, the whole becomes more con- 
genial than a naked surface. White sand or broken 
quartz is frequently used, but it soon becomes dirty, 
and has a harsh and dry appearance. 
In the arrangement of the plants some degree of 
order must be observed, so that every specimen plant 
of a species should be seen to advantage, and if the 
collection is extensive, and the house has different 
aspects as regards light and shade, then it is desirable 
to arrange the plants according to their habits and 
requirements ; thus, at Kew, the division Eremobnja 
occupy the whole of the south side of the house; this 
division being less sensitive to the effects of the sun 
or deficiency of water than the more extensive division 
Desmobrya, wdiich, on account of their thin texture, 
very quickly suffer from dryness or too much exposure 
to the sun ; therefore the north side of the house is 
best for them. 
The natural direction of the fronds is the most 
pleasing, whether upright, pendulous, or spreading. 
