Latex and its Functions . 
205 
subsequently to be well known among the rubber-tappers of 
the Amazon valley, the home of Hevea brasiliensis. However, 
it seems, up to this, hardly to have been mentioned in the 
literature on the subject of rubber-tapping, although it is one 
of the most important points connected with the yield of 
caoutchouc from Hevea. 
The increased quantity of latex from a new incision in the 
bark made 10 to 15 centimetres distant from an old one, 
can hardly be due to the formation of new milk-vessels, since 
the wound-response and increase in question may be recog¬ 
nizable after the lapse of a single day. 
This response to wounding seems an important point relative 
to the function of latex, and a very practical one regarding 
the tapping of Para rubber-trees ; and it needs further investi¬ 
gation. It will also be interesting to see whether other 
rubber-trees, such as Manihot Glaziovii (Ceara rubber), behave 
in a similar manner. 
Full details respecting the practical results of experiments 
on this wound-response are to be found in the Circular men¬ 
tioned at the beginning of this paper. 
VI. A Peculiarity in the Exudation of Latex from 
THE SEVERED BASE OF THE PETIOLE OF HEVEA BRASI¬ 
LIENSIS, Miill.-Arg., AND Plumiera ACUTIFOLIA, Poir. 
Hevea brasiliensis . The leaf is trifoliate, with a long 
petiole, slightly swollen where it joins the stem. The large 
lanceolate leaflets are attached by very short stalks to the 
petiole. 
The following points may be noted regarding the flow of 
latex:— 
1. When the petiole of a mature foliage leaf is cut or 
broken sharply across at its base (Plate XII, line A-B, 
Fig. 1), no latex exudes from the injured surface attached to 
the stem, whereas the surface of the detached petiole is imme¬ 
diately suffused with latex. 
2. When the severance is made quite close to the stem 
