round the stem. Naturally its direction is less sloping the 

 more often it envelopes the stem. By enlarging the wound at 

 intervals of a few days in the manner above indicated, the whole 

 bark of the stem will in time be removed. Of course it was 

 desirable in my experiments to have the tapping operation 

 performed in the customary manner by trained workmen. 



Mr. Pit was kind enough to instruct his men accordingly. In 

 the first instance he put at my ^disposal a He'vea tree, eight 

 years old, that had never been tapped. At the height of, say 

 a man's chest, the girth of the tree was 50 cm. Tapping began on 

 November 8th, 1907. From the height of 1,28 cm, the incision was 

 carried one and a half times round the tree in a basal direction. 

 A distance of 50 to 52 cm. was left between the spiral curves. 

 Details of the manner of tapping can be seen on the accompanying 

 diagram. (Compare diagram 2.) It represents the bark of the 

 tree, as it would appear to the eye, reduced to one-tenth of its 

 size, if the cylinder of bark were cut open longitudinally and spread 

 out flat. Tapping was performed daily, alternately with the 

 Bowman parer and the Bowman pricker. Of course I ascertained 

 frequently, that the tapping cuts were properly executed. Tapping 

 was continued up to February loth, 1908. On February nth, the 

 tree was cut down for examination. 



Before I communicate the result, I must refer briefly to the 

 examination of small pieces of wood and bark, made at various 

 times during the tapping period. For we derive from it some 

 interesting information with regard to the changes in the distribu- 

 tion of organic substances occasioned by tapping. 



On December I5th, bits of bark, 5 cm long, were excised 

 from the tree for the first time, that is, 36 to 37 days after the 



beginning of tapping, one bit (a'l, from 

 just above the incision. 10 cm from its upper 

 end, another (b), in a vertical line below (a), 

 just undrr the wound (Compare diagram 

 i), a third, (c), from the bark on the 

 opposite side of the stem, 100 cm above the 

 incision. Starch was found only in (c), 

 but not in (a) or (b). By treating with 

 Frhling's Solution, no difference in the 

 quantity of reducing sugar contained in (a), 

 (b) and (c) was apparent. 



Diagram I. 



