134 ORCHIDS FOR EVERYONE 



if the batch or house of plants is treated as a mass much in the 

 same general way that we treat a bed of Cabbages, instead of being 

 considered and cared for as so many individuals. 



Temperature and ventilation are matters that must be con- 

 sidered together. It is a fatal mistake to believe ventilation is 

 chiefly for the reduction of temperature. It is not. The chief end 

 of ventilation is to supply the plants with plenty of fresh air. 

 Fixed temperatures are also a great mistake. In the Odonto- 

 glossum house the Winter temperature should range from 45° to 

 ^^° at night, and from 50° to 60° by day, the lowest night 

 reading being reached on very cold, windy or frosty nights, and 

 the highest day reading being reached on mild and bright days. 

 During the Summer the night figures should be 50° to ^^"^^ and 

 the day figures ^^° to 6^°. The latter figure will be often 

 reached, and probably often exceeded, in the hottest part of the 

 Summer. With high temperature and plenty of ventilation there 

 must be a free distribution of water among the pots and over floors 

 and wall spaces. This process of " damping down " may have to 

 be performed half a dozen times on hot, dry days, while a thorough 

 hosing of the paths outside the house will at such times temper the 

 dryness of the air. Ventilation by means of the ventilators set in 

 the highest part of the house (top ventilators), is not an unmixed 

 blessing, because the free circulation creates a very dry atmos- 

 phere, therefore this sort of ventilation must be given with great 

 discretion. Bottom ventilation is safer in two ways. In the 

 Winter the air admitted through the bottom ventilators is 

 warmed by its contact with the hot-water pipes, which are 

 usually set under the side or front stages. In the Summer 

 time it is possible to have these lower ventilators open on both 

 sides of the house, consequently, if there is plenty of moisture- 

 holding material on the stages and also on the floor spaces 



