378 
A most interesting and ol>s CUre point wass raised by him re the 
connection of the laticiferous -o the vital processes of the 
p^ant ; as this is a subject of profou >y oractical interest it will not 
be out cf place to inquire into that connection. 
Mr. Wright, in alluding to the feeding of the laticiferous system > 
referred to a section of interest in that apposition was seen on the 
part of a milk tube with a vessel in the young Hvood. The question 
to beginwith is, what is latex? It is generally thought to be a 
waste product, but an analysis of latex (in F. elastica ) shows that it 
contains proteids, carbohydrates, the emulsion being due to the 
suspension of the “rubber element” in the mother fluid. 
It is interesting to know why a single species plant requires such 
a large system for the storage of its products, while the general 
tendency of plants do not point in the same direction. 
As pointed out the latex tubes occur in the “bark” in the rubber 
tree and do not encroach upon the xyiem. If we turn to other trees 
we see that the tree as a w’nole takes part in the deposition of its 
waste products. Thus in Pin us the resin passages occur in second- 
ary xyiem, while in other plants raphides are seen deposited in the 
vessels of the plant. -Besides it is interesting from this point of 
view to recall that distinct milk passages can be observed in the 
stipules of the F. elastica, and we know that of all forms of modified 
leaf the stipules come- nearest the original. 
k ( *t us inquire whether there are any data for suggesting that 
fate* may be in its earlier stagey a food for the plant. We know 
that in a u green-leafed plants starch granules can be seen in the 
guard-cells roU nd each smmata. There is reason to believe that the 
change ol carD 9n dioxide to starch takes place through the interme- 
diation of the formation of premc aldehyde, the later stages being 
only concerned with hydrolyses and polymerisations, two processes 
easily attained in the plant ov ng to the large cell surfaces in- 
volved. 
, Tiing this physiological fact further we know that the starch 
can be used by the organism only as sugar, and the excess of starch 
is dm "d in various parts of the tree. 
Ket n mind the properties of living protoplasm in the direc- 
tion of selection and polymerisation it is not difficult to imagine that 
the carbon dioxide may be changed to a member of the acetylene 
series, Isoprene either directly by the phenomena of hydrolysis 
and polymerisation or by more complex changes. 
\\ e know as a matter of fact that the decomposition products of 
rubber give isoprene and levulmic acid, of which more anon. Iso- 
prene, though of the open series of carbon compounds, like the 
other members of its series, readily polymerises to dipentene of the 
terpenes and of the closed or ring carbon compounds; the formula 
ior dipentene is (C 10 H 16 ; now on the distillation of the “rubber 
element ' Caoutchouc we get the identical isoprene and dipentene 
and the formula (empiric) of Caoutchouc is (C, e H lfl )n: This is of 
importance as showing that Caoutchouc is a polymer of dipentene. 
