Gums, Resins, 



196 



[September, 1910. 



15 times as stated, but in varying 

 numbers from 15 to 24 times. Taking 

 the average, this works out at 200 trees 

 tapped 20 times (19 8) instead of 200 trees 

 tapped 15 times. This reduces the yield 

 per tree per tapping toO 75 ounces, in- 

 stead of 1 ounce, and thus the Experi- 

 ment falls more into line with the others. 



In Experiment VI. there is the same 

 error ; the trees in alternate day tapping 

 were not all tapped 51 times, and the 

 average works out at 150 trees tapped 

 33 times (32"6). Correcting for this, the 

 alternate day yield per tapping comes 

 to 0"61 ounces. This, however, is still less 

 than the yield per tapping in daily 

 tapping, and some additional explan- 

 ation must be sought. This is found in 

 Straits Bulletin Vol. V., p. 460, where it 

 is stated that the poor return during 

 November, December, 1905, and January, 

 1906, may be partly explained by recalling 

 that the heaviest fruit crop recorded 

 terminated in December, the heavy fruit 

 crop and tapping period being conter- 

 minous. Nearly all the alternate day 

 tappings (28) fall within this period.* 



The last point brings out a fact which 

 is shown in the detailed tables, but is 

 not clear from table 5. The tappings, 

 daily and alternate, were carried out in 

 each experiment on the same group 

 of trees. Therefore they had to be 

 carried out at different times. Con- 

 sequently climatic influences have full 

 play, and the results are not comparable. 

 This is the explanation of the result 

 in Experiment VI. If we are to gain 

 any valid information on the relative 

 value of tapping at different intervals, 

 the experiments must be conducted at 

 the same time in order to avoid cli- 

 matic differences. 



Objection may further be taken to 

 these experiments, and to the manner 

 of setting them out in table 5. At first 

 sight it would appear that in Experi- 

 ment I., for example; the trees were 

 tapped 105 times consecutively. But 

 reference to the detailed results of this 

 experiment shows that they were tapped 

 15 times in July, 1904, 25 times in August- 

 September, 1905, 25 times in June-July, 

 1906, and 40 times in April-May, 1909. 

 The same kind of thing occurs in every 

 other experiment. In no case were the 

 trees tapped for more than 40 times 

 consecutively, and in the majority of 

 cases the number of consecutive tap- 

 pings was not more than 25. The con- 



* In these last two paragraphs I have referred 

 to errors in the table of alternate tappings 

 only j there are others in the daily tappings. 



ditions of the experiment are therefore 

 not such as would obtain on any estate. 



Experiment VI. states that 150 trees 

 were tapped daily 78 times for 680 lbs- 

 7| oz. of rubber, and 150 trees were 

 tapped every other day 51 times for 

 187 lbs. 9| oz. of rubber. Working out 

 the details we find that for daily 

 tapping, 150 trees were tapped Novem- 

 ber-December, 1909, 30 times for 251 lbs. 

 8 oz., and 150 trees were tapped June- 

 July, 1906, 25 times for 268 lbs. 7 oz. ; 

 and for alternate day tapping, 150 trees 

 were tapped November-December, 1905-6. 

 28 times, for 138 lbs. The remain- 

 ing tappings were done in December- 

 January, 1904-5, aud consisted of 120 

 trees tapped daily 23 times for 160 

 lbs. 8£ oz., and SO trees tapped on 

 alternate days 23 times for 49 lbs. 9| oz. 

 But in making up table 5, each of these 

 is reckoned as 150 trees tapped 23 times. 

 Similar mistakes occur in every experi- 

 ment, except No. I and IV. In Experi- 

 ment V., 200 trees tapped 15 to 24 times 

 are reckoned as 200 trees tapped 15 

 times. In Experiment III., 60 trees 

 tapped daily, 18-23 times (average 21), 

 and 80 trees tapped on alternate days, 

 14-15 times, are reckoned as 60 trees 

 tapped 20 times aud 140 trees tapped 15 

 times. In Experiment II. ,80 trees tapped 

 14-18 times, and 40 trees tapped 16 times 

 are reckoned as 120 trees tapped 18 

 times, and 120 trees tapped 16 times- 

 The result of Experiment IV., as stated 

 in table 5, atones for the absence of 

 errors of this kind by a mistake in 

 the total yield ; the trees were tapped 

 103 times for 610 lbs. 11 oz. of rubber, 

 not for 673 lbs. 9f oz. 



Summing up we find that 



(1) The calculations based on table 5 



are incorrect. 



(2) In no single line of- table 5 are 



the results of an experiment 

 correctly stated. 



(3) The daily and alternate tappings 



are not comparable because they 

 were carried out at different 



seasons. 



(4) The tappings were not continued 



long enough to furnish useful 

 results. 



Table 5, with the tappings averaged 

 correctly, would appear to be :— 



