66 CENTRAL AMERICAN RUBBER TREE. 



DIRECTION AND SHAPE OF INCISIONS. 



The tubes which produce the milk of Castilla and other rubber trees 

 are so slender and thread-like that the creamy liquid would not flow 

 from their cut ends if it were not forced out by pressure. Some 

 writers seem to have assumed that the liquid is actually compressed 

 inside the tubes, or that the walls of the tubes are stretched by the liquid 

 they take up. A more probable view is that recently advocated by 

 M. Lecomte," that the pressure is due to the tension of the bark, and 

 that it is mostty exerted in a transverse direction. If we add to this 

 the fact that nearly all the tubes extend lengthwise, a transverse cut 

 would reach the maximum number of these and would thus for two 

 important reasons secure more milk than one of the same length in 

 any other direction. A cut along the trunk would be the worst, since 

 it would reach the fewest tubes and relieve the tension of the bark 

 most. Oblique cuts are intermediate, the more horizontal the better. 

 .M. Lecomte hesitates to recommend transverse cuts lest they may 

 prove injurious to the tree; but if a short transverse cut will bring as 

 much milk as a longer oblique gash there seems to be no real reason 

 why it should be more harmful, providing, of course, the tree be not 

 girdled, or too much bark be not cut away at one level. The practi- 

 cal difficulty with transverse cuts lies in the fact that it would be 

 much more difficult to collect the milk, some of which will stay in the 

 cuts, while the surplus will run down the trunk of the tree in many 

 driblets instead of being brought together at the point of the V-shaped 

 incisions generally used. The desirability of making the cuts as nearly 

 transverse as possible should, however, be considered, and in districts 

 where, as in eastern Guatemala, dependence is placed entirely on the 

 "scrap" rubber, most of which coagulates in the cuts or on the sur- 

 face of the trunk of the tree, it may be feasible to make the cuts nearly 

 or quite transverse. Indeed, this is what Dr. Preuss describes as cus- 

 tomary on the El Baul plantation in Guatemala: 



For tapping they use an instrument made out of a bush knife (machete). The end 

 of the blade is for this purpose bent back until a groove is formed about broad 

 enough to lay a finger in. The cutting edge of this groove is well sharpened. With 

 this instrument the workmen tear horizontal gashes in the bark of the trees, and 

 indeed over a half or three-quarters of the circumference of the trunk. The grooves 

 are cut at distances of 1 J feet, one above another, up to the principal branches. The 

 milk at first flows out in drops, which fall to the ground. They let these go to waste 

 because the quantity is only small and this milk is very watery. But in a minute or 

 two the dropping ceases and the milk which then oozes out is pulpy and remains in 

 the furrows, where it hardens into strips of rubber. In two days these strips are 

 pulled out, washed, and dried in the shade, and are then ready for market. Drying 

 in the sun causes the rubber to become sticky and should be strictly avoided. The 

 trees are tapped four times a year; each time another side of the trunk is operated 



« Journ. d'Agri. Tropicale, 10: 100. Translated in Agriculture Bui. Straits and 

 Federated Malay States, 1: 382. 



