THE MEXICAN AND CENTRAL AMERICAN SPECIES 
OF SAPIUM. 
By Hewry Pirvier. 
INTRODUCTION. 
Among the Costa Rican species of Sapium there is one common in 
the central valley of San José and known to the natives under the 
name of yds or 7és, a word that probably originated in the extinct 
Guetarti language. The milk of this species is used by boys as a bird- 
lime.* Small sticks are smeared with the fresh milk and placed near 
some food that will attract the birds, and if any of these happens to 
alight on one of the sticks, its feet adhere so strongly that it can not 
fly away. With the object of ascertaining the presence or absence of 
rubber in the milk of that species, I started a few years ago some pre- 
liminary investigations. The subject of my first few experiments was 
a tree growing in a hedge near San José. Its trunk was about 80 cen- 
timeters in diameter, and it measured nearly 3 meters from the ground 
to the limbs, but it had been kept cut back with the hedge, so that the 
ramification was all new growth with very large, fleshy leaves. These 
furnished an abundance of a watery latex which, after desiccation, was 
found to contain traces of rubber and a very large amount of a sticky, 
resinous substance. Later I realized through personal experience the 
fact, already very well known, that the milk of young Castilla trees 
and other rubber plants also yields mostly resinous substances and 
comparatively little rubber, so that the conclusiveness of these first 
experiments against the utility of the Costa Rican Sapium became 
doubtful. 
I had no opportunity, however, to continue my researches under 
better conditions and had almost adopted the opinion that none but the 
high Andean species of Sapium, known from Colombia and Ecuador, 
were rubber-producing trees, when my attention was attracted by 
various articles from different sources, all of which contributed to 
throw new light on the really important réle of several species of this 
genus as contributors to the suppl) Vv of South Amer! ican rubber. 
a The milk was used for the same purpose in “Jamaica. “(See footnote, p. 162.) 
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