i893. EVOLUTION IN THE GUIANA FOREST. 41 



present time (September) the mango has been flowering for two months, 

 and trees may be seen in different stages from unopened flower buds to 

 half-grown fruit. The fruit will ripen from December to February, 

 when the great mango- season will be over, and only a fruit here and 

 there be obtainable until June and July, when a second crop matures. 

 The result of the two cycles and the difference in flowering and 

 fruiting of individual trees is that most tropical fruits are obtainable 

 more or less for six to eight months of the year, being, however, far 

 more plentiful during the few weeks of each season when the 

 majority ripen. 



It is hardly necessary to bring evidence in favour of individuality 

 among cultivated plants. Every gardener and florist knows that it is 

 impossible to predict absolute uniformity in the offspring of a single 

 plant, even when the greatest care is taken to prevent crossing. 

 Everytliing goes to prove that the same individuality can be found, 

 more or less, throughout the plant world, but it is especially recog- 

 nisable in tropical plants. The analyst notes differences in the 

 amount of active principle in samples of drugs, the tanner in barks, 

 while the wood-cutter accounts for one log being more durable than 

 another by false notions of the moon's influence. 



Leaving the trees of the forest, which are so difficult to investi- 

 gate particularly, and coming to the epiphytes which grow upon 

 them, we find specialisation carried to extremes in the great -^rchid 

 family. The collector, the dealer, and the grower will all admit 

 individuality here. The varieties are so numerous as to be almost 

 impossible to define. Not only are there differences between plants 

 of the same species from several localities, but even among those 

 collected within a small area. Any grower who knows his plants will 

 recognise one from another, and be continually on the look-out when 

 each flowers for the first time. On account of these differences, 

 orchid collecting is particularly fascinating. A dozen plants of one 

 species are bought at auction, and, until they flower, no one can tell 

 how they will turn out. We often hear of unique specimens, but the 

 fact of the matter is every one is unique. 



In the case of the orchids, there can be no suspicion of man's 

 interference. Artificial selection may have been concerned in the 

 development of other families, but not of this. The wonderful varia- 

 tions in the leaves of crotons and flowers of the hibiscus family may, 

 perhaps, be due, to some extent, to their appreciation by the Poly- 

 nesians, but the Indians of Guiana wear no garlands, nor do they 

 cultivate a single flower for ornament. It is not only among the more 

 showy genera, such as Cattleya and Odontoglossum, that individuality is 

 conspicuous, but brassias, gongoras, and even some of the more 

 insignificant families, are equally variable. 



It is only in our gardens that we can observe the many variations 

 of large trees, and here we have, unfortunately, but few species from 

 the forest. By studying the vegetation on every trip to the bush, we 



