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the normal secondary bark containing laticiferous vessels. But the 

 sections made through the bark, on which the pricker had been 

 used, showed a very different picture. Wherever the teeth of 

 the pricker had penetrated to the neighbourhood of the cambium, 

 the latter had formed a new bark with many stone-cells, but 

 without, or almost without, laticiferous vessels. Where, however, 

 the teeth of the pricker had not penetrated through the 

 inner cortex, new bark had been formed containing laticiferous 

 vessels, that were arranged irregularly, or (as in the case of 

 normal secondary bark), arranged in rows. The entire surface 

 of the bark was uneven ; everywhere between the cuts of the 

 pricker the cortical tissue had bulged outwards. From this it 

 would appear that the bark on the tapping spots is renewed much 

 more evenly if the knife is used exclusively, than if knife and 

 pricker are used alternately. In the former case, therefore, the 

 bark ought to be much sooner ready for re-tapping than in the 

 latter. By making further observations and by comparing, under 

 the microscope, sections of the renewed bark after a longer 

 period of time than it was in my power to give, it will, I feel 

 sure, not be difficult to ascertain how much longer the latex 

 takes to ripen after the use of the pricker than after the use of 

 the knife, and whether the greater quantity of latex obtainable 

 by the use of the pricker, compensates for the longer resting- 

 period required before the commencement of another tapping 

 period. For this reason I feel justified in warning planters 

 against the use of the pricker. And this the more, as I have often 

 noticed on estates, that the teeth of the pricker had penetrated 

 into the wood. The pricker is evidently an instrument that is out 

 of place in rational estate cultivation. It would be better to make 

 the tapping cuts somewhat deeper and to remove a little more 

 cortex and bast. 



