Marcu, 1907.] THE ORCHID REVIEW. 87 
varying height of the plants, and they should not quite touch anywhere 
—that is to say, although the supports of the upper stage rest on the 
lower, there should be an interval of a few inches, so as to permit the 
air to circulate between them. Slate slabs with iron supports are the 
best for the lower stage, and the other may be fixed or movable, but a 
trellis-work of roughly-planed battens, nailed together with cross pieces, 
and supported on bricks is both economical and efficient. 
A few studs and wires from the roof are also useful for suspending 
small plants in baskets, which, however, should be arranged so as not 
to drip on to the plants beneath, and not to obstruct too much light. 
Paved floors should be avoided for Orchid houses, as affording too 
little moisture for evaporating purposes. Some good sand thrown on an 
earth basis and covered with a trellis work is much better. Fluted tiles, 
like those used for stables, are more durable than trellis-work, and as 
the interstices hold water they are very suitable for the actual paths, 
but gravel should be used beneath the stages, in which shade-loving 
foliage plants can be grown, such as selaginellas, small ferns, pileas, &c., 
and this will provide a large evaporating surface, and give that genial 
moist atmosphere so important for successful Orchid culture. 
The question of ventilation was dealt with in the preceding paper, 
but it should be added that the top ventilators should be made to lift 
up, not to slide down, so that it will not be necessary to close them 
during rain. Sliding ‘hit or miss” ventilators are best for bottom venti- 
lation, but if shutters are used a piece of wire netting should be stretched 
over the opening to keep cats or other animals out. 
PottinG Orcuips.—This is a subject of the greatest importance if a 
collection is to be kept in thriving condition, and one in which the 
beginner is apt to make mistakes. It should not be done periodically 
regardless of other considerations. When the plants begin to grow and 
Produce new roots is the time to repot, if the operation should be 
required, and on this point the grower must use his discretion. When 
plants are in this stage he should notice whether the plant has outgrown 
its pot, and if not whether the compost and drainage are in good condition. 
In the former case a shift into a larger pot is advisable, but in the latter a 
little re-surfacing with new compost at most will suffice. If a plant 
appears unhealthy the compost will probably be in a like condition, in 
which case it should be all cleared away, all decayed roots cut off, and the 
plant should then be put into new compost, in the smallest size pot 
possible. 
The potting materials and method of using them have been so fre- 
quently dealt with by able writers in the Calendar of Operations that the 
point may be passed over lightly. Good fibrous peat, with an admixture 
