48 RUBBER AND 



supply being cut off, the starvation and ultimate death 

 of the roots is only a matter of time, if the ringing is 

 complete and permanent. Under these circumstances 

 the tree may linger on for several years, but all its vital 

 functions will be greatly impeded. Such ringing may 

 occur more or less completely as the result of injudi- 

 cious or unskilful tapping. Any cut or prick which 

 reaches the cambium cannot fail to sever a certain 

 number of the channels through which the sap passes 

 down to the roots; and it is probable that the weakening 

 effect of excessive tapping is often due as much to the 

 starvation of the roots as to the removal of the latex. 

 Any system of tapping which involves the cutting or 

 pricking of the whole circumference of the tree at one 

 time is bad from this point of view. In fact it must be 

 considered advisable never to tap more than one-third, 

 or at the most one-half, of the total circumference of the 

 tree at any one time. 



Special stress has been laid by Fitting on the damage 

 caused by tapping too wide an area, and the views of 

 this observer undoubtedly carry great weight; although 

 some authorities consider that he has taken an unduly 

 serious view of the effects of such a process. Micro- 

 scopical examination shows that the functional con- 

 ducting tubes of the bark are mostly situated very close 

 to the cambium, inside the main layers of latex vessels. 

 Consequently the process of paring, if carried out with 

 sufficient skill, need scarcely affect the conducting tubes. 

 This may account for the fact that on some estates the 



