The physiology of latex production was discussed in Chapters in and IV as fully as is justified by our limited knowledge of the subject The present section contains a few general remarks in relation to tapping. One of the chief troubles of the latex collector consists in the washing away of the latex which occurs in wet weather, owing to the rain water which streams down the trunk of the tree. Rainy days generally make up a large proportion of the tapping season, and if tapping is stopped whenever there is heavy rain, the loss of yield will be considerable. A simple system of guttering has recently been introduced in Ceylon, which can be fitted to the tree above the tapping area, with the object pf keeping the latter dry.

Another reason for keeping dry the tapping area, lies in the fact that this region is more susceptible than any other to the attacks of disease germs. A constant watch should therefore be kept on the tapping cuts, and at the first sign of disease tapping should be suspended. There are two reasons for ceasing to tap a diseased tree; firstly in order to allow the individual tree to recuperate, and secondly to avoid the transference of infection to other trees by means of the tapping knife.

In the absence of visible signs of disease, certain cuts are sometimes found to yield little or no latex, whilst there is still a comparatively free flow from other cuts. When this is the case, the hint should be taken and the tree rested, otherwise definite disease is not unlikely to supervene. For a description of particular diseases and their treatment, reference may be made to Chapter VIII.

At the bottom of the conducting channel a tin spout should be fixed into the bark, in order to throw the latex clear of the surface of the tree into a cup placed on the ground below. The practice of pushing the edge of a metal collecting cup into the bark at each day's tapping may lead to injury, and is not to be encouraged.

In all operations dealing with latex the utmost attention must be paid to the virtue of cleanliness. Latex is as easily contaminated as milk, a substance with which it has many properties in common. Not only should the standard of cleanliness in the factory be at least equal to that adopted in an up-to-date dairy, but the avoidance of all kinds of dirt should begin from the moment when the latex first makes its appearance upon the surface of the tree. Collecting cups, paring knives, and the bark itself should all be kept scrupulously clean. All scrap should be carefully removed from the tree before paring commences. In order to save the precious hours of the early morning, this may very well be done during the afternoon of the day before tapping.

Plantation Yields

Finally, some idea may be given of the actual yields of rubber obtained upon estates. The amounts recorded vary very largely on different properties, but the following figures may be taken as representing approximately the average yields obtained with moderate systems of tapping in Ceylon and the Malay Peninsula respectively.

Table XXIX

Age of trees, years

Ceylon

Malaya

Per acre, lbs.

Per tree, lbs.

Per acre, lbs.

Per tree, lbs.

45

5o

.4

100

.8

5-6

100

.6

150

1.0

6-7

150

.8

200

1.3

7-8

200

1.2

250

1.6

8-9

250

1.5

350

2.2

910

300

1.9

400

2.5

Very much higher yields than these have been obtained under favourable conditions, and larger average yields may probably be anticipated in later years, now that the importance of careful and moderate tapping during the early stages is beginning to be fully realised.