The Supplement to the Tropical Agriculturist 



our last issue, in Ceylon there is a strong feeling 

 that thinning out should not be done until the 

 effect of cultivation has been proved, the plan- 

 ters holding that view stating that what culti- 

 vation cannot do, neither can wide planting. 

 Thinning 20 ft. by 20ft. 



In these blocks our Malayan correspondent 

 suggests that trees having burrs, disease, etc., 

 should be selected for thinning, and that the 

 number should be reduced to 75 per acre, in 

 this case he also believes in removing all badly- 

 grown trees or any which do not yield a fair 

 quantity of rubber, and irrespective of the 

 appearance of the estate, he maintains that any 

 exceptionally fine trees should be allowed full 

 space for further development, presumably by 

 the removal of all others. In gambling circles 

 this might by some people be regarded as put- 

 ting all the money on one horse. 



Thinning 24 ft. by 12 ft. 



Here the same methods as in 20 ft. by 20ft. 

 clearings are recommended, but the trees are 

 to be reduced first of all to 100 per acre instead 

 of 75 as in the previous case. The object for 

 leaving a larger number of trees is that the ex- 

 isting trees, not being so well grown, do not in 

 the meantime stand in need of so much space to 

 develop in, and by the time they have filled the 

 spaces caused by the removal of a number of 

 trees further thinning can be considered. 



It is, as he point out, quite obvious that the 

 removal of 142 trees per acre from areas carry- 

 ing 217 trees per acre as in 20 ft. by 10 ft,, would 

 reduce the yields of rubber per acre to an un- 

 desirable extent for some time. The same argu- 

 ment applies with a distance of 24 ft. by 12 ft. 

 Other Distances. 



He suggests that areas planted 20 ft. by 10 ft., 

 should be thinned-out to 80 trees per acre, and 

 those planted 30 ft. by 10 ft. down to 95 trees 

 per acre. Where there are fewer than 100 trees 

 per acre, such as 24 ft. by 24 ft., or 24 ft by 20 ft., 

 he suggests that only those trees which are giv- 

 ing little or no rubber, or which hamper the 

 development good trees should be removed. 



On closely planted areas, such as 18 feet 

 by 12 feet, 15 feet by 15 feet 12 feet, by 12 

 feet, 18 feet by 15 feet, every alternate row may 

 be removed, leaving distances of 18 ft by 24 ft, 30 

 ft by 15 ft, 24 ft by 12 ft, and 30 ft by 18 ft. 



Here our correspondent expresses the view 

 which we emphasized in our original editorial 

 to the effect that it is difficult to out cut every 

 alternate row in every instance, because rows 

 selected for removal may have very good speci- 

 mens and those which are retained may possess 

 very bad ones. 



Tapping of Tubes Selected fok Removal. 



It will be remembered that on this point many 

 of our correspondents held divergent views. The 

 majority were in avour of extracting as much 

 rubber as possible from the trees to be thinned- 

 out, but there were a few gentlemen whose 

 opinions we value, who held that trees to be 

 removed should be promptly uprooted and all 

 parts removed and burnt. Our Malayan corres- 

 pondent emphatically advises that all trees sel- 

 ected for removal be tapped heavily for six or 

 nine months, and finally cut out, the last stage 

 being executed, if possible, during the winter- 

 ing or low yielding season in March-April, We 

 welcome any further views which managers of 

 estates may have on this very important sub- 

 ject. — India- Rubber Journal, Nov. 9. 



A NEW SOURCE OF RUBBER. 



" EUPHORBIA LORIFOLIA " 

 IN HONOLULU. 

 Some interesting notes on Euphorbia Lori- 

 folia as a possible source of rubber and chicle 

 (resin) are contributed in the form of a press 

 bulletin published by Mr. W. McGeorge, assis- 

 tant chemist, and Mr. W. A. Anderson, superin- 

 tendent of the rubber sub-station in connection 

 with the Hawaii Agricultural Experiment station 

 at Honolulu. While there is room for doubt, 

 says Mr. McGeorge, as to whether scientists will 

 ever be able to duplicate the natural rubber 

 with a synthetic product, it is almost an abso- 

 lute certainty that a synthetic substitute will in 

 the near future ba made an article of commerce. 

 Detailing the present rubber-producing trees he 

 goes on to say that the attention of the station 

 has been called to the plant above-meutioned, 

 which contains an unusually large quantity of 

 latex, and occurs in large numbers in the is- 

 lands. So far as it known this particular species 

 of Euphorbia is found in no other part of the 

 world, being a native of Hawaii, and no infor- 

 mation appears to be given as to whether it will 

 thrive elsewhere. The latex is a white viscous 

 fluid with a strongly acid reaction, and a rather 

 pluasant aroma peculair to itself. It is highly 

 combustible, quickly darkens on contact with 

 the atmosphere ; it does not ferment readily 

 and can be preserved indefinitely without even 

 coagulation or separation, by the addition of a 

 small quantity of formalin. At the outset it 

 was found that most of the ordinary methods 

 of coagulation were without apparent effect 

 upon this latex. &.cetic acid produces no 

 appreciable coagulation even on long stand- 

 ing, while a host of other methods were 



