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, 0. Rossii, 0. membranaceum, and 

 some other Mexican species should be grown in baskets or 

 pans ; 0. coronarium and its varieties in oblong baskets ; 

 0. Londesboroughianum on rafts. Odontoglossums require 

 abundance of water, but are easily injured if allowed to get 



