GENERA AND SPECIES 99 
grown in well-drained pots. The compost in which they 
are grown used to be formed exclusively of Orchid peat and 
Sphagnum-moss, and, where these materials can be obtained 
of good quality they have never been improved upon. 
There came a craze in some collections for putting the 
Odontoglossums in leaf-soil, which ended in disaster, al- 
though it indicated that a proportion of dry leaves (not leaf- 
soil) may be used in the compost with advantage. Scarcity 
of good Orchid peat brought about the introduction of 
Polypodium fibre and Osmunda fibre, both excellent mate- 
rials when prepared as recommended in the chapters on 
Potting Epiphytal Orchids, and Hybrid Orchids. For the 
general repotting of those requiring it September is the best 
month, but in early spring the plants should be examined 
in order to repot those which need immediate attention. 
The Odontoglossum house must be kept cool at all seasons, ° 
and the necessity to have lower night temperatures must be 
strictly recognised. Free ventilation should be provided, 
but at all seasons when drying, east winds prevail, especially 
in winter and early spring, the bottom ventilators should be 
only opened slightly, the top ones being kept closed ; the laps 
of the glass of the roof will admit sufficient air. Moisture 
should be freely distributed about the house by syringing 
beneath the staging and between the pots in summer, but 
in winter the houses, if kept at the prescribed low tempera- 
ture, will be moist without much water being distributed. 
Odontoglossum citrosmum, O. Rossii, O. membranaceum, and 
some other Mexican species should be grown in baskets or 
pans; O. coronarium and its varieties in oblong baskets ; 
O. Londesboroughianum on rafts. Odontoglossums require 
abundance of water, but are easily injured if allowed to get 
