COLLECTING THE LATEX. 83 



the present day.(^ It consists of a central channel which may 

 vary in length from I to 6 feet, into which shorter oblique 

 incisions, alternating with each other on either side of the 

 central channel, lead at an angle of about 45 and at distances 

 varying from 9 inches to I foot apart. Subsequent operations 

 consist in shaving the lower surface of the oblique incisions at 

 varying intervals of time until the whole of the bark between 

 the oblique cuts has been pared away.,) An objection to this 

 method of tapping is that the amount of latex obtained from 

 the excision of bark for the perpendicular channels is not 

 commensurable with that yielded by the same amount of bark 

 excised in an oblique direction, for the reasons previously 

 explained. On the other hand its adoption effects a consider- 

 able saving of labour as compared with the V method, as it 

 is only necessary to place one collecting vessel at the base of 

 each vertical channel. 



Some planters prefer to excise all the bark from one side of 

 the perpendicular channel before commencing to tap the opposite 

 side. Others elect to divide up the trunk of the tree into three 

 or four divisions and excise all the bark from each division in 

 rotation. Whichever modification of this system of tapping be 

 adopted, its drasticity will obviously largely depend upon the 

 care taken to protect the cambium and the wood, the quantity 

 of bark pared away at each operation, and the period of time 

 allowed to elapse between successive tappings. 



SPIRAL INCISIONS. 



What is known as the " Full Spiral " (vide Fig. 1 3) is considered 

 one of the most drastic methods of tapping yet evolved, but yields 

 the largest amount of rubber in a specific time. This method of 

 tapping is also reported to have been employed by Nicaraguan 

 rubber collectors more than thirty years ago. Briefly stated it 

 consists in making a series of spiral, parallel, incisions, about 12 

 inches apart, round the trunk ; these usually commence at a 

 height of 6 feet from the ground and end at the base of the tree. 



The number of incisions on any particular tree is conse- 

 quently regulated by the circumferential measurement of the 

 trunk at the point where operations commence. Subsequent 

 tappings are effected by shaving the bark off the lower side of 

 the incisions. 



