RUBBER PLANTING 69 



on without intermission. We shall presently see that 

 there is some falling off in yield about this period, but 

 that the reduction is not nearly so great as would be 

 expected on the theory of the origin of the latex in the 

 leaves. Moreover the composition of the latex in the 

 leaves differs considerably from that in the stem. 



During the experiment the tree was steadily in- 

 creasing in girth, and new latex vessels were constantly 

 being added to the bark by the activity of the cambium. 

 The amount of bark tissue thus added in three years 

 over the area actually tapped was nearly equal to 

 the amount removed, but in other parts of the tree 

 much less. The new latex vessels contained in the 

 renewed bark are therefore only responsible for a com- 

 paratively small proportion of the latex obtained. The 

 greater part of the latex still unaccounted for can only 

 have been produced in one way, and that is by the 

 active secretion of latex in existing laticiferous tissue. 

 In fact we arrive at the important conclusion not by 

 any means universally accepted that the laticiferous 

 tissue of the bark is an organ for the manufacture of 

 latex as well as for the storage of latex. 



There is evidence that this process of manufacture 

 is specially active in the immediate neighbourhood of 

 the wounded area. In an experiment carried out on 

 29 trees of an average girth of 26 inches, the whole of 

 the outer bark on one side was removed to a height of 

 six feet by tapping on a six-V system for a period of 

 only six months. Tapping was immediately continued 



