THE ORCHID REVIEW. 105 
ORCHIDS ABROAD AND AT HOME. 
Notes of a Lecture delivered before the Members of the Kew Gardeners’ Mutual 
Improvement Society on December 7th, 1896, by Mr. R A. Rolfe. 
(Concluded from page 71.) 
WE now come to the important question of food supply. An Orchid 
requires a certain amount of food, in order to build up its tissues, just 
the same as any other plant, but the best method of supplying this is 
not always an easy matter. Plants are unable to assimilate solid substances, 
and take up their food in a liquid state. When the roots are in the soil, 
they take up the water containing various substances in a state of solution, 
and it is easy to supply liquid manure ; but in the case of plants with aerial 
reots it is a more difficult matter. Then again, many Orchids are generally 
supposed not to like liquid manure, though a few terrestrial species are 
undoubtedly benefited by its use. It is certain, however, that if any Orchid 
were planted upon a perfectly insoluble medium, cultivated in a pure 
atmosphere, and watered with distilled water only, it would speedily die 
from sheer starvation. The great question is, How do epiphytic species, 
whose roots are chiefly aerial, obtain their food? If this question could be 
answered satisfactorily, it would be a very easy matter to supply it artificially. 
Among terrestrial species some are confined to a limestone or calcareous 
district, and will speedily die if removed to a non-calcareous soil, 
simply because one element of their food supply is absent. Others live 
chiefly upon humus, or decaying vegetable matter, which is easily supplied, 
in the form of peat or leaf mould. Swamp-loving species must be naturally 
well provided for in this respect, as the water in such places is always 
charged with decaying vegetable matter. Many epiphytic species grow 
among accumulations of dead leaves, or on the stems of tree-ferns, palms, or 
various dicotyledonous trees, and although the latter may seem a rather 
unpromising medium, it is certain that the necessary food is there, or is 
contained in the water which reaches their roots. 
Aerial roots, however, in many instances are not attached to anything, 
the young absorbent apex being free in the air, and such roots evidently 
obtain their food from the moisture in the air and the gases it contains. The 
futility of pouring manure-water on to the compost in which such plants 
may be grown must be apparent. It might as well be poured about the 
floor of the house, or anywhere else in the vicinity, and this affords a clue to 
a possible means of supplying the necessary food. 
It has often been remarked that the secret of growing many Orchids 
largely consists in supplying a suitable atmosphere—that is, one containing 
the proper amount of heat and moisture, according to the season, and pre- 
vented from becoming stagnant by suitable ventilation. Some cultivators 
