mediately under the eye of the grower. It is often the case
that albinos, rare varieties, and new species are allowed to get mixed
up in the general collection, and a plant that could not be replaced may
be hidden by the commoner things which are not of so much consequence.
In the case of the best spotted varieties of _Odontoglossum crispum_,
albino Cattleyas, and other exceptionally rare things, it is a good plan
to arrange a batch of them together in the most suitable part of the
house, or to place each on an inverted flower-pot at intervals along the
staging, thus bringing them into prominence and facilitating the
inspection of each at all times. Some use wire plant stands instead of
inverted pots, but the moisture-holding flower-pots are preferable, if
they are inspected occasionally to see that they are not harbouring
insects. Albinos and fine varieties of Cattleyas and Laelias could be
grown in suspended Orchid pans or baskets, to take them out of the
general collection, and so grown they would make better progress than if
placed on the stages. In the case of any plant not making satisfactory
growth it is often beneficial to place it on an inverted pot to bring it
more prominently under notice.

CHAPTER XII

DISEASES AND INSECT PESTS

There is very much in the old-time advice, "Grow your plants clean," for
a very large proportion of Orchid diseases and insect pests are due to
errors in cultivation, more especially in the regulation of the
temperature and the ventilation. Insanitary houses lower the vitality of
the plants, and vegetation, like human beings, is a prey to disease when
kept in unhealthy conditions.

Spot, or Orchid disease, exhibits itself in various forms. It is caused,
as scientists say, by different micro-organisms, but in effect it is
practically the same whether in the form known as "Spot," often seen in
Phalaenopsis, Aerides, and Vandas, or in the decayed and blackened
pseudo-bulbs of Cattleyas, especially _C. Warscewiczii_ (gigas), which
from an apparently healthy plant may develop a diseased condition of the
pseudo-bulbs, and become useless in a few days. In all such diseases it
will be seen that the tissues have collapsed, the result being brown or
blackish spots on leaves or bulbs. Imperfect nutrition from lack of
healthy roots is a frequent cause of this mischief, for Aerides and
Vandas which have been affected with "Spot" recover in the new growth,
for a time at least, if a sat