28 - 



On December 22nd, pieces of bark, (a) and (c) were again 

 cut from similar places, and also a small piece of bark from the 

 wound near (a), (c) again contained a quantity of starch, but 

 (a), even at a distance of 10 cm from the wound, contained none, 

 nor did the bark on the wound. 



I have also taken bits of bark from similar places on another 

 Hevea tree, eight years old, that had been tapped for a fairly 

 long period, and had been thrown down by a storm, on December 

 I2th, 1907, and have examined them for starch. The tapping 

 liad been performed on the half spiral system, so Mr. Pit said, 

 and had been continued from April to June, and from August 

 to October, 1907. Starch was completely wanting in (a) and (b), 

 while it was abundant in (c). 



From these observations it is evident that soon after the 

 commencement of tapping, starch disappears from those parts of 

 the bark which are next to the cuts, not only below, but also 

 .above them, and that after the cessation of tapping, some interval 

 of time must elapse before it can be reproduced even above the 

 incision. In the case of the fallen tree, for instance, one and a 

 half months had not sufficed to reproduce starch above the 

 wound. Evidently the starch in the neighbourhood of the wound 

 is claimed by the vigorous creative activity, which during the 

 period of tapping and for some time after, is at work in the 

 cambium below the wound. 



These discoveries prove at the same time, that contrary to 

 my first impression, the examination of small pieces of bark does 

 not enable us to draw conclusions sufficiently as regards the 

 influence of tapping on the distribution and circulation of sap 

 in the stem. 



For that purpose, it is on the contrary necessary, to sacrifice 

 the whole tree, at least for the present, till we have more data 

 on which to carry out less disastrous methods of investigation. 



For this reason I saw myself faced by the necessity, of 

 having my experimental tree, that had been tapped on the full 

 spiral system, felled on February nth, that is after 96 days of 

 tapping, and long before the whole bark had been removed. 

 The wound was as yet only 12 cm broad. (Compare diagram 

 2.) The stem was cut into sections with a saw, after which parings 

 of the bark were systematically examined for starch and reducing 

 sugar. The wood also was at first examined in thin sections 



