ami;kic.\.\ STdU.w i-uoDrcTioN 23 



than 2 inches above the scar in at least one horizontally tapped speci- 

 men. One case of the vertical extent of the effect of a wound stimulus 

 in pine has been observed by the writer where tlie structure more than 

 () feet above the wound was modified. 



The Depth of the Streak or Searificafioti. — The cut should probably 

 be only deep enough to expose completely the surface of the last 

 formed wood since all the ducts are produced in the new wood which 

 grows after the cut is made. There appears to be no advantage 

 (unless it intensifies the stimulus) to be gained from cutting deeply 

 into the wood when scarifying gum trees. 



The proportion of the circiimfcrenec to he cut to give the l>est yield 

 would have to be determined by experiment. Tt is suggested, however, 

 that about one-third of the circumference should be covered with the 

 uncut bark. Clean cutting with sharp tools should be required. 



Checking the Entrance of Decay Through the Exposed Wood. — It 

 would be very desirable to make experiments to reduce, if possible, 

 the attack by fungi or bacteria and the discoloring of the wood near 

 the scarifications by perhaps painting them with some substance that 

 would be toxic to or prevent the entrance of organisms and would at 

 the same time not be water soluble or volatile or sufficiently poisonous 

 in character to injure the gum for any of the purposes for which it is 

 used. It is possible that a quick drying rosin mixture or some other 

 coating might be devised for the purpose. This would also prevent 

 the often harmful drying out of the sapwood, which takes place through 

 the exposed surfaces. It would be desirable to apply the coating when 

 the first cut is made so that it would in no way clog the ducts forming 

 later in the new wood above the scar. 



The Position of the Scarification. — The l)est yields of oleoresin may 

 possibly come from the early low chipping at the butts of pine trees. 

 Therefore, it is a point worthy of consideration to determine where the 

 optimum position as regards both yields and ease of working is to be 

 found. 



When to Scarify the Trees. — Although there are no data on this 

 subject for red gum, results from experiments on wounding pines to 

 induce excessive flow of oleoresin, might at least be indicative. It has 

 been found in the case of longleaf pine that there is a distinct advan- 

 tage to be gained in quantity of yield and in securing an early flow of 

 gum as the temperature rises in the spring, by placing what is known 

 as the "advance streak" on the timber. This consists in chipping or 



