CULTIVATION. 
349 
practice of potting, it is a rule with, many gardeners 
to remove all the old drainage crocks, the centre thus 
becomes a mass of soil, which in time becomes com- 
pact, inert, and useless, liable to become stagnant, 
and in time causing the plant to sicken. This is 
avoided by preparing and retaining the old drainage. 
This mode of drainage is, however, only necessary for 
plants required to be permanent in botanical collec- 
tions. Its utility in prolonging life is verified by some 
yet existing plants of Proteacece at Kew, some of 
which are forty, and others above sixty years of age. 
What has here been stated may be considered as a 
general rule for the greater number of the Fern 
family, such as are usually found in ordinary collec- 
tions of a hundred species, more or less. But in this 
extensive family there are many possessing some pecu- 
liar nature, and a few examples of these require to be 
specially noticed. 
The group which has been termed Epiphytal, 
consists of the genera Davallia, Goniophlebium , 
Drynaria, Phymatodes, Pleuridium, Platycerium, lo- 
mariopsis, Polybotrya, and others of like habit, charac- 
terized by a true and highly-developed rhizome or 
sarmentum, generally creeping, and adhering by 
their fine fibrous roots to the surface on which they 
grow. Their positions in their natural homes are 
generally on more or less perpendicular surfaces of 
moist and shaded places of rocks or ordinary soil, 
where decomposing vegetable matter abounds as a 
surfacing. They are often found on trees, and with 
many species of Polybotrya and Lomcvriopsis this 
•seems to be their true position, and often by their 
vigorous growth, the trees are clothed with them in 
