commerce in the past, especially during periods of feverish need 
to increase production. 
To judge from the literature, one might assume that Micran- 
dra had enjoyed a relatively major role in the world rubber 
supply. Most literature reports of the exploitation of Micrandra 
for rubber are either without foundation or else are erroneous 
repetitions of one or more of the earlier botanical explorers who 
noted this exploitation as an isolated observation not connected 
with a critical economic study of the industry as a whole. 
In the earlier literature, it seems that there are but two reports 
on Micrandra by field botanists with first hand experience and 
whose statements should, for this reason, carry greater weight 
than most other literature references. Richard Spruce, who col- 
lected the type material of the genus Micrandra (including 
Cunuria) in the Rio Negro basin of Amazonian Brazil, failed to 
mention the utilization of Micrandra latex in commercial rubber 
production, an industry which, during his sojourn in the region 
(1851-1854), was beginning its great development on the basis of 
seringa or Hevea. In his posthumously published notes, he wrote 
(Spruce, R.: [ed. A. R. Wallace] “Notes of a botanist on the 
Amazon and Andes” | (1908) 508): “On the Vaupés, I met with 
two trees (2427, 2479 hb.) of a genus apparently not far removed 
from Siphonia [Hevea], which yield pure rubber and are also 
called by the Indians xeringui .. .” E. Ule, who carried out 
extensive surveys on rubber plants in the Amazon regions in the 
early years of the present century, stated (Ule, E.: “Veranlassung 
und Verlauf von Ules Expedition nach den Kautschukgebieten 
des Amazonenstromes” in Tropenpflanz. Beih. 6 (1905) 1) that, 
although Micrandra produces a good rubber, the trees are sel- 
dom exploited because the latex cannot be mixed with that of 
Hevea and because it is too troublesome for the rubber tappers 
to cut it to the exclusion of Hevea. In another report on his 
rubber studies, Ule (Ule, E.: “Die Kautschukpflanzen der Ama- 
zonas Expedition und ihre Bedeutung fiir die Pflanzengeogra- 
phie” in Engler Bot. Jahrb. 35 (1905) 670) reported merely that 
Micrandra siphonioides is found to be frequent in the rubber 
forests of the Rio Negro and elsewhere. 
From these two references, apparently, has stemmed a flood 
of reports, occasionally highly misleading, in both popular and 
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