44 



to the full or half herring-bone incisions, and whether too great 

 an injury will not be caused to the tree, if as is the custom, all 

 oblique cuts are connected by \a vertical drainage canal. As 

 regards the first question, the V-shaped, herring-bone incision 

 has probably an advantage over the half herring-bone incision, 

 because in the case of the V-shaped incision, it is possible for 

 the organic food material to flow obliquely from both sides out 

 of the old bark, down into the V-shaped bridges of bark between 

 the incisions, which are disposed one above the other, and because 

 in this case it is only a question of short channels. In the case of 

 the half herring-bone incision, the downward flow can come only 

 from one side and the distance is double. I do not share the 

 doubts that have been expressed with regard to the vertical 

 drainage canal. I do not think that a canal of that description can 

 do much damage to the bark, provided it is not made either too 

 deep or too wide. 



And lastly, it will be necessary to discuss the important 

 question, whether or not the pricker should be used. This 

 instrument possesses undoubtedly certain advantages. For one 

 thing, the cuts with the knife need not be made so deep into the 

 inner cortex, and in consequence, a smaller amount of bark will 

 be removed, and secondly, it is not necessary to cut away strips 

 of bark so repeatedly, and the tapping period can therefore be 

 prolonged. But it would be a mistake to imagine, that the pricker 

 does not cut through all channels in the bark down to the cambium 

 on the entire tapping surface, just as deeper cuts with the knife 

 would, and that labourers, using this instrument, are not extremely 

 liable to injure the cambium. 



But the question, whether the pricker is suitable, must be 

 decided by the way in which its use affects the renewal of bark. 

 If there is no difference in the results as compared with those 

 obtained by the deeper cuts with the knife, the pricker can be 

 used without hesitation. As, strange to say, no investigations 

 on this subject have so far been made, I ordered in the case of 

 the tree tapped on the herring-bone system, the knife only, and 

 the knife and the pricker combined, to be applied alternately to 

 the tapping-spots situated one above the other. I made a minute 

 anatomical examination of the bark, that had been renewed in 

 the course of four to five months. Wherever the pricker had not 

 been used, bark had been produced which did not differ from 



