8 PRESENT-DAY GARDENING 
and style, can be seen instances suggesting the evolu- 
tionary process; these would be more common but for 
the number of connecting links which have dropped out 
in the great struggle for existence, 
CHAPTER III 
DIFFICULTIES TO OVERCOME 
SOME of the difficulties which the cultivator of Orchids has 
to contend against arise from the fact that his houses have 
to accommodate plants which have been brought from widely 
separated countries, or from different altitudes in the same 
region. They therefore require very different cultural con- 
ditions, especially in the matter of temperature. 
Consideration of the climatic conditions under which 
the plants are found growing in their native habitats is very 
helpful to all engaged in Orchid culture. Many problems 
have already been worked out by the experience of culti- 
vators, but some of the conclusions have been arrived at 
only after costly failures. In the early days of Orchid 
culture, before the advent of the modern Orchid house 
with its improved methods of ventilation and means for the 
promotion of humidity, the great mortality among culti- 
vated Orchids was caused by excessive heat and drought. 
Even at the present day more mischief is done by excessive 
heat than by cold treatment, 
