rubber collectors consider that a remarkably rich rubber dis- 
trict where the rubber trees average one to the acre. The mean 
annual temperature of the regions is about 83° F., with an 
annual range between 73° and 95°. The rainy season begins 
in October. By January the whole region for 2,000 miles is 
more or less submerged and the floods do not begin to disappear 
until June. During the "dry" months, July, August and Sep- 
tember, there are frequent thunderstorms. The home of this 
tree is a hot, steamy, truly tropical, rich alluvial plain, almost 
under the equator and only slightly elevated above sea level. 
The tree seldom occurs at elevations greater than 600 feet. Its 
native habitat, so widely different from the climate of Hawaii, 
undoubtedly precludes the probability of its successful cultiva- 
tion in these islands. There are eight or ten other rubber-yield- 
ing species of Hevea, some of them undescribed by botanists, all 
native of the upper Amazon valley. vVhile some of these grow 
at higher elevations and in lands not periodically submerged 
their total yield is comparatively inconsiderable in quality and 
amount. 
White Rubber. This is produced by a number of species of 
trees of the genus Sapium, native in the north-western portion 
of the South American continent. 
Sapium, Tolirnense, Hort., is a native of the mountains in 
South Western Colombia, making its best growth at an altitude 
of 3700 to 6000 feet . The tree is said to grow with extraordi- 
nary rapidity, reaching a height of fifty feet with a trunk one 
foot in diameter in six years. It will grow at a higher elevation 
than coffee. The rubber is of very excellent quality. This is 
certainly a promising variety for introduction into Hawaii. 
Sapium verum Hemsl. A forest tree 60 to 75 feet high with 
a trunk 3 feet in diameter, native to Ecuador and southern 
Colombia. It reaches its best development at an elevation of 
5,500 to 7,500 feet and grows up to 10,000 feet. This tree is 
the principal source of the "caucho bianco" of Ecuador. 
Sapium stylare AEuell. Arg. A large forest tree occurring at 
an elevation of from 3,000 to 6,000 feet on the wet mountain 
slopes from Venezuela to eastern Ecuador. The mean tem- 
perature of the region where it grows ranges from 56 = to 61° E. 
Other species of Sapium growing under truly tropical condi- 
tions at lower elevations are S. tapuri Ule.. S. eglandulosum 
Ule, S. utile Preuss, and S. Marmieri Huber. The milky sap 
of the latter is poisonous. These species all require higher 
temperatures and a greater degree of humidity than is found 
in Hawaii. 
