The Guiana Orchids. 15 



where the moisture is always uniform, is fibrous peat 

 admissible, as alternate wetting and drying produce 

 conditions that are very unfavourable. The aerial roots 

 turn away from anything they dislike ; the plant will 

 rather loose its hold and fall to the ground than remain 

 attached to wood which has begun to decay. Even 

 where we can see no signs of this the behaviour of the 

 plant is a sure indicator of its commencement. 



Anyone who travels in the forest may see that the 

 process of decomposition which goes on there is quite 

 distin6t from that on the coast. Great trees crumble 

 down into a rich brown humus, with but little sourness 

 or fungus growth. True, the white threads of what 

 appears to be one kind of mould are common enough, 

 but those yellow, grey and black fungi so common about 

 our palings and other out-door woodwork are wanting. 

 It follows therefore, that although orchids may thrive 

 amid the decaying leaves that lodge in the tree-forks of 

 the forest, they cannot endure the dry rot of the coast. 

 Alternate wet and dry as compared with almost uniform 

 moisture seems to be the cause of these great differ- 

 ences, which are well exemplified by the dark coffee- 

 coloured water of the pegass savannahs when contrasted 

 with that of the stagnant pool, which is yellow or green 

 and lies on a bed of stinking black mud. 

 3. — WHAT ORCHIDS ARE, 



Before enumerating the Guiana species it would be 

 well to define what is an orchid. At an exhibition in 

 Georgetown some years ago, a common species of 

 bromelia was exhibited under the name of a " parrersite" 

 and the person who showed it was quite indignant that 

 no prize was given for his "orchid." This is an illustra- 



