THE CENTRAL AMERICAN RUBBER TREE 221 



is then converted into crepe by means of a washing 

 machine. 



On many estates in Tobago the cream of rubber globules 

 is poured on to wet cotton sheets, stretched in a frame, 

 and allowed to drain, when a sheet of rubber is obtained 

 which is subsequently stripped from the cloth. 



Centrifugal Methods. — Castilloa latex can be quickly 

 coagulated by spuming it m a centrifugal machine. On 

 manj'" of the estates in Mexico the " Empire " cream 

 separator is used for the pm'pose, and the rubber is obtained 

 in the form of a solid cone, which can afterwards be 

 converted into sheet or crepe if desired. Smith's centri- 

 fugal machine which is used in Tobago enables the rubber 

 to be prepared in the form of sheets. 



Yield of Rubber from Castilloa Trees. — In considering 

 the question of the yield of rubber from Castilloa trees, it 

 must be borne in mind that the different species or varieties 

 of the tree occurring in Central America are stated to vary 

 widely in the amomit of rubber which they furnish, so 

 that the results obtamed from trees in a particular locality 

 camiot be taken, without further investigation, to repre- 

 sent the yield from trees growing in other districts. 



The information available regarding the amount of 

 rubber obtainable from wild Castilloa trees is very in- 

 complete, and it is not possible to give any trustworthy 

 figm-e for the average amiual yield per tree. It has been 

 recorded that large forest trees have yielded as much 

 as 10 to 20 lb. of rubber, or even more, at a single tapping, 

 but it is probable that tlie higher yields are exceptional 

 and that they would not be maintained on repeated 

 tappmg. More recent information indicates that the 

 earlier estimates of the amount of rubber fiu:nished by 

 the wild trees were too high and that the maximum 

 annual yield from large trees does not usually exceed 

 the lower figm'e mentioned above, viz. 10 lb. per tree. 



With reference to the yield of rubber from cultivated 

 CastiUoa trees more definite information can be given, 

 and it will be convenient to summarise the data under the 

 different countries. It may be stated that on the whole 

 the results of tappmg plantations of CastiUoa trees up 

 to ten or twelve years old have been disappointing, the 

 yields of rubber bemg much less than was anticipated. 

 Individual trees and small groups of trees have given very 



