of the tissues above and below the section any more than one 
prevents from pressing the body by doubling its width so that 
under these circumstances the latex should flow as strongly as 
possible. 
A longitudinal section on the other hand gives a different result, 
for the lips of the wound will tend to separate and the tension will 
become weaker 
As has been shown several causes combine to make the trans- 
verse cuts the most efficacious for allowing the escape of the latex. 
But are we to say that such cuts are entirely to be recommended ? 
This is not our idea, for the collector has not only the actual present 
collection to look to, but the possibility of future collections. Now 
1 do not say that from this point of view the transverse sections 
might not be disastrous and the more so the longer they are. 
In fact the wound made in the bark heals more or less rapidly 
by the formation of fresh tissues and from this cause the laticiferous 
vessels at first continuous, are now separated in segments, which 
are the shorter the nearer the cuts are to each other. It follows 
that the later cuts only meeting with fragments of laticiferous 
vessels will only let out very little latex. 
In my opinion for reasons stated above it will be most suitable 
if one makes transverse or oblique cuts in a vine or tree to make 
a certain number at the same height, say three metres from the 
ground and to recommence some time after a little lower and so 
on till the latest cuts are close to the ground. Leaving then the 
tree to recover for a sufficiently long period, at least a year, new 
tissues will form inside the bark and into these new tissues the 
original laticiferous vessels will penetrate. After this period, occu- 
pied by the tree in producing new tissues containing laticiferous 
tubes one can make the cuts again in the same way. In no case 
must complete circular incisions be made as these would arrest the 
circulation of the sap and seriously risk the life of the tree. Too 
wide cuts also must be avoided, for the healing of a wound is more 
difficult and long the further the edges are from each other. 
It would not be difficult to arrange a programme of a certain 
number of experiments and observations to be made by persons 
dwelling in the tropics and having rubber plants at their disposal. 
The results of such investigations would be of much importance 
for the future of the plantations actually organized in various parts 
of the world. On this subject we shall deal again if possible later. 
Henri Lecomte. 
Note.- — It is not correct to say as Bonysson does (Revue Gene- 
rale des Sciences 1899, p • 83 1 ) that “the latex is a sort of ascend- 
ing sap.” I do not think that one can show as yet any proof that 
the latex circulates in the vessels. The fact that latex flows 
unequally from the two lips of a cut is due to the difference of 
tension of the tissues on both sides and the flow may be much 
greater from the upper lip of the cut than from the lower one. I 
have proved this in the case of Landolphia dor id a, Benth, in the 
Conservatories of the Museum, 
