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juice, opaque, and very similar to that of the mammal, though when 
administered internally, it produces lethargy, from its being trans- 
formed in the stomach, into rubber. 
This opaqueness is due to the presence of numerous globules 
of a matter, which, when dry, turns elastic, and which is 'held in 
suspension, in an aqueous fluid, clear, and having the appearance 
of an emulsion. I hi s aqueous fluid contains various albuminous 
substances held in solution. 
Pure rubber composed of these globules, consists solely of Car- 
bon and Hydrogon in defined proportions C 4 H 7 - 
The latex circulates by a system of longitudinal cellular veins 
or vessels. These vessels are to be found in the inner layer of the 
bark, between it and the wood and known as the cambium. From 
this cambium the two layers are formed, the external producing 
the bark, and the internal the wood, ft is in the internal layer 
that these laticiferous vessels reside. 
The bark is usually ten millemetres in thickness while the cam- 
bium is from 2 to 3 millemetres. 
During the fruiting season, or at the shedding of the leaves, 
that is, from May to July, the milk is then abundant, and is then 
rich in rubber, from this being the time the sap descends. During 
this epoch, a kilogramme of milk will produce half a kilogramme 
of rubber. When the sap ascends, the milk is then poor in rubber, 
is aqueous, producing no more than 200 grammes of rubber to 
every kilogramme of milk. 
The milk from the branches and boughs, is always watery, is 
deficient in globules, and its chemical composition does not appear 
the same as that exuding from the trunk. Milk should only be 
extracted from healthy trees, adult and after tluy have flowered. 
A tree does not attain its full growth till after 20 to 25 years, 
though at ten years a tree can be bled, but not before it has flow- 
ered, at least twice. 
It is true that in the Amazons, milk is extracted from trees of 
five years growth, but as I have observed, in small quantity and of 
poor quality, demonstrating the fact that at this age, the latex 
coagulates before there is time to prepare it, giving a product of 
very inferior quality. 
Taken also the milk, even in the case of adult trees, above two 
metres from the ground, it will tend to sicken the tree or to shorten 
its milk producing period. Some ambitious men, careless of the 
sacrifice it entails, go the length of erecting a mutd (fixed ladder) 
in order to tap the upper part of a tree, a proceeding which should 
be prohibited and which has been one of the causes which has led 
to the extinction in some places of rubber producers. 
To be continued. 
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