ORCHIDS AND EVOLUTION — COSTANTIN. 347 



of the delicate aerial plant. No one would think of making a fish 

 live out of water. How could one expect that a species accustomed 

 to a free epiphytic life would accommodate itself without injury to 

 a low terrestrial existence? 



The proper mode of cultivation once found was perfected little by 

 little. For certain types found exclusively in the tops of trees there 

 was devised a plan of fastening them to a piece of wood with brass 

 wire together with a little moss to furnish permanent moisture. An 

 aquatic moss, sphagnum, seemed particularly suited to fill this role 

 because of its power of imbibing water. It was in 1841 that Paxton 

 first mentioned it as having been employed by him in the Duke of 

 Devonshire's greenhouses. It remained to discover the compost com- 

 monly employed for most orchids, which consists of an intimate mix- 

 ture of sphagnum and fibers of fern roots (peat of the English, 

 Osmunda, Polypodium), after these two elements have been finely 

 cut, this mixture covering fragments of broken pots used to furnish 

 drainage (potsherds placed in the lower part of the receptacles in 

 which the plant is put). But all the tropical orchids are not aerial, 

 as was soon learned, and when the lady's-slippers arrived to furnish 

 the handsomest ornaments of European greenhouses they were culti- 

 vated in pots, for they were terrestrial plants, a little fresh earth 

 being added in their case to the compost which suited most orchids.^ 



There was no thought of cultivating species accustomed to a tropi- 

 cal climate except in very warm greenhouses; and in 1830 Lindley, 

 who contributed so much to the progress of the science of orchids, 

 insisted upon the necessity of maintaining for cultivated types the 

 two factors which characterize equatorial climates — heat and hu- 

 midity. It was immediately after this that the technique was per- 

 fected which made it possible to obtain in greenhouses an elevated 

 temperature along with an atmosphere charged with vapor to the 

 point of saturation by frequent sprinkling not only of the plants 

 but of the walks, walls, and benches, thus reproducing artificially the 

 constant rains, the torrents which descend almost daily upon many 

 equatorial countries. 



Unfortunately this method of treatment, which succeeded wonder- 

 fully with certain plants, resulted, with many others, in lamentable 

 failure. Lindley and other horticulturists in 1830 agreed that all 

 tropical plants are accustomed to a uniform climate, but beneath the 



1 A recent and important perfection of this method consists in treating differently the 

 species whicli live in calcareous soil and those which shun it. The latter should be 

 moistened with rain water if tho running water of the region where they are grown 

 contains lime (as is usually the case in France) ; and as potsherds for drainage pieces 

 of broken flower pots are used. In the case of species preferring calcareous soil, like 

 Cypripedium iellatnlum, concolor, niveum, Godejroyae, drainage is furnished by pieces of 

 mortar ; in addition, pieces of calcareous rocks are mixed with the compost, and the 

 plants are moistened with ordinary water. 



