164 THE RUBBER TREE BOOK 



of 1908 and the whole of 1909, 1910, 1911. During the whole 

 of this time the experiment was carried on without a break. 



AVERAGE YIELD PER TAPPING. 



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



1908 IOO IO7 148 158 169 210 163 



1909 57 72 86 91 113 121 108 



1910 58 69 67 96 118 115 115 



1911 87 78 143 169 176 154 



" One of the best-yielding trees in Row III. had, unfortu- 

 nately, to be cut out early in 1910 owing to canker. No allow- 

 ance is made for this fact in the above table, but in the table 

 which follows one-fifth of the actual yield is added to the yield 

 for Row III. 



" It was obvious, early in 1910, that some of the weaker 

 trees of Row I. had suffered from the rate at which they had 

 been tapped, and it was not thought desirable to continue 

 operations on the renewed bark. 



" Now it might be thought possible to draw the conclusion 

 at once from the above table that the yield of rubber per 

 tapping increases clirectry with the interval 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 tap- 

 ping 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. 

 (Allowance is made for the fact that Row III. contains 9 trees only.) 



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



No. of 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. 



