May, 1912.] 



387 



val between successive tappings up to an interval of eight days (row VI,). But it 

 has to be remembered that row I. is always in a later stage of tapping than row II. 

 and so on ; whilst down to the end of 1910 the earlier tappings give in all cases 

 higher yields than the latter ones. Towards the end of 1911, however, the yields 

 began to increase. This increase was much greater in the case of the rows 

 tapped at longer intervals. The following table shows the yields for January 

 and February, 1912 :— 



Period of Sixty days, January and February, 1912. 

 Groups of Ten Trees.* 

 II. III. IV. V. VI. VII. 



No. cf tappings ... 24 17 12 10 8 7 



Total yield grammes ... 1,932 1,540 2,080 2,163 2,020 1,572 

 Average per tapping ... 80 90 173 216 252 224 



The average yields from rows V, VI. and VII. for these two months are 

 greater than any yields previously obtained from rows I. II. and III. 



From the above table the remarkable fact appears that after 3i years' steady 

 tapping (making full allowance for the fact that Row III. row contains only 

 nine trees), rows IV., V. and VI. each yielded a larger amount of actual rubber, from 

 12, 10 and 8 tappings respectively, than rows II, and III. from 24 and 17 tappings 

 respectively. 



Turning to the figures for 1909-11 it is of interest to record approximately 

 the crop per acre which the yields recorded would produce. The result expressed 

 in lbs. is as follows :— 



Average Annual Crop per Acre. 



II. III. IV. V. VI. VII. 



1909-10 ... 566 480 381 364 315 257 



1911 ... 653 620 605 565 490 360 



Now the yield for 1911 has increased over the average yield for 1909-10 in 

 every case, but the increase is decidedly greater in the case of the rows tapped at 

 longer intervals. Expressed as percentages of the average yields for 1909-10, the 

 increases are as follows : — 



II. HI- IV. V. VI. VII. 



17 29 59 55 56 38 



In view of the figures for January and February, 1912, the conclusion presents 

 itself that we are rapidly approaching a period when the crop gathered once a week 

 will exceed the crop gatheied every three or four days. According to the figures so 

 far available an interval of 6£ days (rows V,) appears likely to give the best final 

 result. All the tables here given show a distinct falling off in the case of row VII, 

 indicating, as might have been expected, that nine days is too long an interval. The 

 best yield per tapping is given throughout by row VI, and the best total yield for 

 January and February, 1912, by row V. To revert to the subject of the early part of 

 this article, it these were the only facts available, we should be ju&tified in recom- 

 mending a period of renewal of eight years as superior to one of four years. 



We do not wish to labour this point too far, as it is desirable to know the 

 further course of the experiment before coming to a final conclusion. 



It must not be forgotten that the present experiment was made upon trees 

 upwards of twenty years of age planted at a distance of only 12 x 12 feet. The facts 

 are, however, remarkable, and of such importance that it seems desirable to place 

 them at once in the hands of the public. There can be no doubt that the facts so far 

 available point to the desirability of an increase in the interval between successive 

 tappings. 



* Allowance is made for the fact that row III, contains nine trees only. 



