10 DENDROBIUM. 



below which the plants would languish and even perish if subjected 

 to it beyond a period of limited duration; and a higher range which 

 it would be most injudicious to attempt to reach by artificial means ; 

 that the plants have alternate seasons of active growth and comparative, 

 if not complete repose, and that during the former they are immersed 

 in an atmosphere always highly charged or even saturated with moisture. 

 As is well known, and from causes that will be occasionally specified 

 in this work, it is impossible to produce in a glass structure, what- 

 ever may be its dimensions, even an approximate imitation of climatic 

 conditions, such as are provided by Nature in distant lands, and to 

 which the plants indigenous to those lands are adapted. This is well 

 seen in the case of the four great essentials of epiphytal plant life : 

 thus moisture must be supplied entirely by artificial means ; the requisite 

 heat is maintained chiefly by artificial means too ; light, especially direct 

 sunlight, except for a short time at midsummer, is present in such 

 diminished intensity as scarcely to amount in the aggregate during the 

 year to much more than one-half of what it is at the equator ; lastly, 

 the quantity of fresh air admitted through the ventilators is entirely 

 dependent on the external conditions of the atmosphere. So great is the 

 effect of the altered conditions of the interior of a glass structure upon 

 the tissues of the vegetative organs of the orchids confined in them, that 

 if, after a few years' sojourn there they were taken back to the country 

 of their birth, in however healthy a state they might appear to be, and 

 affixed to the stems and branches of trees or set in any such position 

 as their progenitors grew and flourished, or from which they themselves 

 were originally taken, the probability is very great that they would 

 perish during the first dry season through which they would have to 

 pass. • In the hot plains of Moulmein and Lower Burmah, during the 

 dry season, the stems of the native Dendrobes are literally scorched 

 by the blazing sun, and shrivel to half their ordinary size, while during 

 the wet season they are drenched with torrents of rain.* Hence, 

 while a knowledge of the climate of the native countries of orchids 

 and their environment there, is of the highest value to the cultivator, 

 it is still more necessary that he should supplement it with that of 

 the experience gained by the best cultivators — an experience that has 

 taken a long series of years to acquire. 



We will now summarise the principal points to be attended to in the 

 cultivation of Dendrobes. 



Where a collection is grown, of which the aggregate number of plants 

 is considerable, whether the number of species they represent be few or 

 many, it is best to devote a house or compartment of a house mainly to 

 them, for greater convenience of manipulation. Dendrobes may, how- 

 ever, be grown with other East Indian' orchids if care be taken to 

 remove, them from the hotter and damper part of the house where they 



* Col. Benson, in Gard. Chron. 1870, p. 796. 



