132 RUBBER AND 



with the point of a pen-knife, generally heals up com- 

 pletely without any sloughing off of cortical tissue, in 

 spite of the fact that the blade has actually penetrated 

 to the cambium. Such a prick also leads to a con- 

 siderable flow of latex in comparison with the size of 

 the wound inflicted. 



The time required for making small pricks singly 

 is clearly prohibitive of their use as a practical method. 

 For the rapid infliction of a large number of pricks the 

 rotating spur-shaped pricker was introduced by Bowman 

 and Northway in 1905, and has enjoyed a considerable 

 vogue in Ceylon. A single stroke from one of these 

 tools produces a row of pricks running across the bark 

 of the tree. Owing to the difficulty of collecting the 

 latex thus liberated by any other method, the use of 

 the spur-shaped pricker was generally combined with 

 a shallow system of paring. The pricker was run 

 along the paring cut either on the same day or on the 

 day following, and the cut provided a channel down 

 which the latex could flow. The great theoretical 

 objection to this method lay in the closeness of the 

 pricks inflicted on successive days. Although the bark 

 of a healthy tree generally recovered from the operation, 

 there was a considerable sloughing off of cellular tissue. 

 Moreover, in the freshly pricked region the blockage of 

 phloem tubes necessarily produced must have amounted 

 to partial ringing of the tree. It seems clear too, that 

 in some cases the use of this method was associated 

 with an epidemic of woody nodules (see Chapter vill). 



