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process of the formation of rubber may be summed up by saying 
that it is a more or less catalytic action, or to be more accurate 
surface action ; for the re-acting substances to be intimately con- 
nected it is necessary that they be exposed to a large surface as is 
found in the structure of a tree by means of this solution ; hence we 
see that capacity for osmosis must exist between the laticiferous 
system and the vessels, as was shown in the section referred to by 
Mr. Wright. 
It is not easy to explain why it is that such a system exists. It 
may be that the habitat of the plant and its environment may have 
caused this change. The amount of water transpired by a tree 
must partially depend upon the capacity of the atmosphere to take 
up moisture, or the amount of water transpired will be lessened with 
the increasing humidity of the atmosphere. In the Amazon Valley 
where the plant flourishes, the atmosphere must be surcharged with 
moisture so that a large quantity of water is thrown into the food 
circulation of the tree, and this water may be indirectly responsible, 
as we have seen, for the abnormal polymerisation of the products of 
assimilation. It is a bold venture to say so (as I know nothing of 
it myself), because in that cause laticiferous trees must (not neces- 
sarily in all cases) be indigenous in places of warmth and humidity. 
Hence places with a larger rainfall and warmth (for without heat 
the water will be incapable of being vaporised) must evidently 
succeed better in the growing of the tree. 
If also the soil be dry the transpiration current will be small, the 
transpiration will also be small, and so the amount of the latex and 
its percentage of rubber must be smaller than in the other case, and 
the reverse will also be true. 
It was noticed by Mr. WRIGHT that an apparently dead tree may 
yield latex, but we must here recall the recent work of SchWALS- 
BURGER, who showed that transpiration current may or rather really 
does take place in a dead tree, so that though the activity of forma- 
tion of the primary products of assimilation may fail it does not 
follow as a logical sequence that the activity of formation of the 
secondary polysen also fails, especially as polymerisation is a process 
purely chemico-physical in some cases; the water requisite is pre- 
sent, being supplied by the osmosis taking place from the trans- 
piration current, the re*acting surface is present, the products of 
primary assimilation are also present, so that latex may form. 
Lastly, from what has been said previously as regards tapping there 
must be an optimum time when the formation of Caoutchouc is 
finished, but before it has itself polymerised. As regards the age 
for tapping it must be evident that when the plant is young the 
processes of life are quickened so that the products formed must all 
be subservient to the main requirement — viz., the growth of the 
tree, so that even if latex is obtained it would be unwise to tap it. 
I have ventured to bring forward a bold idea, and out of justice 
to myself, I must say it is only a plausible idea, and, as ideas are 
often, may be all wrong, but one experiment which I cannot per- 
