RUBBER PLANTING 79 



least as great as in the case of paring, and with the best 

 possible method of incision some damage is inevitable. 

 Removal of latex without injury to the bark is in fact 

 impossible, but even if this were possible there would 

 still be a limit to the amount of latex which could 

 be extracted without injury to the tree. For the manu- 

 facture of latex necessarily uses up a certain amount of 

 food and energy, and the supply of these in the tree is 

 not unlimited. 



The problem of the physiological effect of paring 

 upon the tree is therefore a complicated one. In addition 

 to the rate of removal of the bark, both the amount of 

 latex taken from the tree and the frequency of this 

 extraction have to be considered. In the experiment 

 with seven groups of trees described above, Group I 

 and some of the trees of Group II may be said to 

 have been overtapped, because at the time when the 

 whole of the outer bark had been removed up to the 

 greatest height convenient for tapping, the renewal of 

 the first area tapped was still imperfect. This result 

 was no doubt partly due to defects in tapping, but with 

 the most perfect tapping there must be a limit to the 

 possible rate of removal of the bark which will permit 

 of proper renewal. 



Let us assume a system by which the whole of the 

 outer bark is removed to a certain height in a given 

 period. Then if at the end of this period the bark of 

 the area first tapped has not renewed sufficiently to 

 allow of a second tapping, it is clear that the proper 



