78 THE ORCHID REVIEW. [Marcu, 1916. 
which last constitute its superlative charm. The flower emits at night a 
powerful and pleasing scent, but is quite odourless during the daytime. 
The foliage is thick and heavy, while the rootstock consists of tough, fleshy, 
rhizomes, from which small trendrils emerge and attach the plant to its 
elected host. B. Digbyana flourishes, in Mexico, solely in the logwood 
swamps of Campeche, affecting mostly the curious ribbed trunk and lower 
branches of the logwood tree (Hzmatoxylum campechianum). These 
‘swamps abound in miscellaneous epiphytal growth, and although tangled 
lianas, thorny shrubs, &c., sometimes render them impenetrable, the 
‘‘ floor,’ more often than not, is relatively clean, and would be easy to get 
over but for its being invariably broken up into numberless islets of a 
heavy tenacious clay about the bases of the trees, the result of the denuding 
waters in the wet season. The annual precipitation is between 60 and 70 
inches, distributed over the six months from May to October. During the 
rest of the year rain rarely descends, except in occasional showers. 
Thus Brassavola Digbyana is capable of withstanding protracted 
atmospheric dryness, its leaf and root system being clearly fitted to the 
accumulation of the requisite reserve of moisture to carry the plant through 
such a hiatus without serious loss of vitality. Moreover, it can bear without 
injury a considerable amount of sunlight when subdued by passage through 
the superincumbent branches and foliage of the woods. The plant 
frequently grows in close company with Bromelias, by which it may 
possibly be protected against dessication. The symbiosis or organic bond 
between B. Digbyana and the logwood tree, whatever it may be in itself, is 
undoubtedly important in its effect, proving, according to the writer’s 
experience, that it provides-a condition necessary to the constitution of the 
plant, to wit, a rapid and free run-off for the water of the torrential rain- 
falls of its native habitat. Moisture retained about its roots inevitably 
leads to its decline and ultimate decay. 
A unique example of ecologic habit in Orchids is presented by 
Coryanthes sp., which almost always grows in the topmost branches of 
large and lofty forest trees. Its roots are composed of a globular mass 
which, in every instance, has been found to be the abode of a colony of 
large, black, vicious ants. It is supposed that these insects excrete some 
substance essential to the life of the Orchid, for it is never found without 
them, and attempts to cultivate the plant, after the eviction of such 
undesirable tenants, have always failed. Mr. James Rodway, in his work 
In the Guiana Forest (p. 130), makes mention of this Orchid, and describes 
the same phenomenon in its affinity there. 
Orchid ecology is well illustrated again by the genus Stanhopea. 
Conspicuous amongst the luxurious tropical vegetation of its natural state 
by its long-stemmed, broad, glossy, dark-green leaves, or, if fortune favour, 
