320 Transactions qfithe London Horticultural Society. 



vegetable and animal matter. In consequence of their position, 

 there cannot possibly he any accumulation of moisture about 

 the roots. They will also grow equally well upon rocks and 

 stones in similar situations. Mr. W. Harrison of Rio Janeiro 

 is mentioned by one of the Society's collectors, who visited 

 him, to cultivate, with the most perfect success, above seventy 

 species upon a wall in his garden at Boto Fozo. 



" We see some of them germinate and grow most luxuriant- 

 ly in damp places, in the stove, upon the sides of the garden 

 pots, and among gravel ; and Dr. Wallich found them in all 

 cases growing equally well upon trees and stones, provided 

 the latter had a certain quantity of mould and moss adhering 

 to them. 



" In the Botanic Garden at Calcutta they are cultivated 

 with success in raised beds of solid brickwork, so contrived 

 as to secure the most perfect drainage ; the soil being rich 

 vegetable matter, mixed with at least two thirds small peb- 

 bles, and covered with a dense layer of moss« 



" Shade seems essential to them ; their natural situation 

 being in deep forests, or among the branches of growing trees. 

 In Brazil they exclusively occupy damp woods and rich val- 

 leys, among vegetation of the most luxuriant description, by 

 which they are embowered. In Nipal, I learn from Dr. 

 Wallich that orchideous epiphytes grow in company with 

 ferns ; and the thicker the forest, the more stately the trees, 

 the richer and blacker the natural soil, the more profuse the 

 Orchideae and ferns upon them. There they flourish by the 

 sides of dripping springs, in deep shady recesses, in inconceiv- 

 able quantity, and with an astonishing degree of luxuriance. 



" In the Botanic Garden at Calcutta it is found that they 

 thrive best under the shade of trees with dense but airy 

 foliage, such as mimosas, especially the Acacia stipulata, the 

 huge stem of which is the more remarkable when compared 

 with the myriads of minute leaflets by which it is formed. 



" High temperature and excessive humidity are together 

 the other conditions essential to the well-being of these plants. 

 The hottest countries, if dry, and the dampest, if cool, are 

 destitute of them ; while there is no instance of a country, 

 both hot and damp, in which they do not swarm. This can 

 readily be shown." 



They are most abundant, in India, in the Malayan Archi- 

 pelago, the mean temperature of which is between 77° and 78° ; 

 and the air is damp to saturation. In Nipal they are only 

 found upon the sides of the lower mountains, where they 

 vegetate among clouds and constant showers. On the con- 

 tinent of India they are almost unknown ; because there, 



