708 RUBBER 



the foreman or " caporal " of the tappers before starting 

 out; but the Mexican Indian tapper is both independent 

 and insubordinate, and no doubt often cuts a young thin- 

 barked tree just as deeply as he would an older thicker- 

 barked one. I have seen prickers and hammer-chisels 

 used for tapping Castilloas, but they were not effective, 

 and, so far as I know, the knife described, or others on 

 the same principle, has not been improved upon, and is 

 not likely to be. 



The Yields of Rubber obtained on the Commercial Scale 

 from Trees of Different Ages. 



To me this question is a delicate matter. In the 

 London India-Rub ber Journal (Quarter Century Number), 

 issued in 1909, a scale of yields was published in an article 

 under my name. I give it here, with apologies, only 

 pleading that my experience then was not so- thorough 

 as it is now; it also related to Castilloas in the Soconusco 

 District of the State of Chiapas, and was as follows: 



" For 6-year-old trees, J Ib. per annum; for 7 years, 

 f Ib.; for 8 years, i Ib.; for 9 years, ij Ib.; for 10 years, 

 ij Ib.; for ii years, if Ib.; for 12 years, 2 Ib." 



As I shall show presently those figures were unduly 

 optimistic. But they had what appeared to me to be a 

 sound basis the published yield of certain wild trees. 

 In April, 1898, Sir Daniel Morris delivered a Cantor 

 Lecture, in which he dealt very ably with the Castilloa 

 rubber tree in many countries. With regard to the yield 

 in British Honduras he was very cautious. I quote from 

 the published lecture: " A large tree of Castilloa, say 

 2 ft. in diameter, is said [is said, please note that] to 

 yield 8 gallons of milk when first cut. Each gallon of 

 milk in the proper season will make about 2 Ib. of rubber. 

 Hence a tree of this size will give a return of 16 Ib. of 

 rubber." 



Now as to those 16 Ib. from one wild tree, I have to 

 say that I have had credible information as to wild 

 Castilloa rubber trees which have yielded more than 

 twice as much. I have heard, credibly, of 50 Ib. from 

 an old Castilloa at one tapping, which, however, probably 



