70 RUBBER AND 



by a similar system on the other half of the tree. 

 The cuts were twelve inches apart, and, after the first 

 day's paring had been carried out, each further cut 

 except the lowest was apparently draining an almost 

 isolated patch of bark, of an average area of 216 square 

 inches. In this case the average thickness of the latici- 

 ferous bark was not more than a quarter of an inch, and 

 on our previous assumption the average volume of the 

 latex vessels contained in one of the isolated patches 

 of bark, could not have been more than 5j cubic inches. 

 The yield in six months from the lowest cut but one 

 was 55 cubic inches of latex, more than 10 of which 

 were drawn off during the first month of tapping. 



There must nevertheless be a considerable move- 

 ment of latex from untapped bark towards the seat of 

 tapping. It was calculated that the largest day's yield 

 from the old tree previously described would have drawn 

 off the whole of the latex from a distance of at least 

 three inches from the tapped surface. As the tubes are 

 never completely emptied, there was probably an actual 

 flow from at least double this distance. In the case of 

 this particular tree the flow continued for several hours, 

 whereas in the majority of trees the cut surface becomes 

 blocked by coagulated rubber in less than one hour 

 after tapping. The structure of the laticiferous system 

 shows that movement of the latex will take place more 

 readily in the vertical direction, but that a lateral flow is 

 also possible. In the older networks a gradual trans- 

 ference of latex may take place over an extensive area. 



