and Magazine of the Ceylon Agricultural Society. 



405 



It will be observed that Dr. Fitting discusses 

 the question from quite a different standpoint 

 from that of the circular. Dr. Fitting is one of 

 the foremost physiological botanists of the day. 



To obviate confusion it may be noted that 

 " secondary cortex" is the cortex tapped by 

 the planter : primary cortex only exists tem- 

 porarily on green stems. 



T, PETOH. 

 (Extract referred to). 



" And finally the important question, whether 

 the pricker should be used or not, must be 

 discussed. This instrument has no doubt cer- 

 tain advantages. In the first place, the cut with 

 the knife need not be made so deep into the 

 inner cortex, and, therefore, less cortex is cut 

 away: secondly, it is not necessary to remove 

 strips of cortex so frequently, and therefore, 

 the tapping period can be prolonged. But the 

 planter must not delude himself into believing 

 that the pricker does not cut through all the 

 food channels in the cortex down to the cam- 

 bium, just as a deeper cut with the knife would 

 and that the worker with this instrument does 

 not all too easily destroy the cambium. 



" But the question whether the pricker is a 

 suitable instrument must be decided by the 

 influence it has upon the renewal of the cortex. 

 If no difference results between the use of the 

 pricker and a deeper cut with a knife then 

 the pricker can be used without hesitation. 

 Since researches on this point have hitherto, 

 most strangely, not been instituted, I have 

 used, in the case of trees which were tapped 

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

 the combination of knife and pricker, on the 

 alternate tapping surfaces (i.e. the uppermost 

 tapping surface was tapped with the knife only, 

 the second with the knife and pricker, the third 

 with the knife only, etc., apparently it was 

 ' half-herring-bone.' It will be noted that this 

 method avoids any possible differences due to 

 the individuality of different trees.— T. P.) 



" I have thoroughly examined microscopically 

 the cortex which was renewed in four to five 

 months. Where the pricker was not used, the 

 cortex, which does not differ from normal 

 secondary cortex, contained many latex vessels. 

 But the sections which were made through the 

 cortex on which the pricker had been used snowed 

 quite a different structure. Wherever the teeth 

 had penetrated to the neighbourhood of the 

 cambium, the latter had constructed new cortex 

 with numerous groups of ' stonecells 1 , but 

 without or almost without any latex vessels. 

 Where, on the other hand, the teoth of the 

 pricker had not penetrated through the inner 

 cortex, the latter contained latex vessels either 

 irregularly arranged, or arranged in rows as in 

 normal secondary cortex. The whole surface of 

 the renewed cortex was uneven : everywhere 

 between the cuts of the pricker the cortical 

 tissue was swollen outwards. Thus it appears 

 that the cortex is renewed much more uniformly 

 on areas tapped with the knife alone than on 

 areas tapped with knife and pricker alternately. 

 The cortex in the former case must also be much 

 sooner re-tappable than in the latter. Further 

 observations, and comparison, under the micros- 

 cope, of sections of the renewed bark after a 

 longer interval than I could give, would deter- 



mine without much difficulty how much longer 

 the ripening of the cortex takes after using the 

 pricker than after using the knife only, and 

 whether the greater quantity of latex which can 

 be obtained with the pricker compensates for 

 the longer resting period required. From these 

 considerations I believe that a note of warning 

 against the use of the pricker must be sounded. 

 The more so as I have often seen in plantations 

 that the teeth of the pricker were forced into 

 the wood. The pricker is obviously an instru- 

 ment which is out of place in rational estate 

 management. Rather should the cut be made 

 deeper, and more cortex and bark removed in 

 tapping." 



FOR CUTS ON CACAO TREES. 



Resin Oil as a Dressing. 

 Resin oil has lately been tried as an antiseptic 

 dressing for cuts and wounds on cacao trees at 

 Grenada, and is reported on very favourably by 

 estate owners and managers, and by the Agricul- 

 tural Superintendent of the island. Coal tar was 

 formerly the chief dressing used for wounds 

 caused by pruning or as the result of an acci- 

 dent, but it is stated that resin oil is superior 

 for the purpose. The Agricultural Superinten- 

 dent of Grenada (Mr R D Anstead, B.A.) re- 

 porting on the matter, mentions that the oil can 

 be applied easily and in a cleanly manner, and 

 it is noticed that the bark of the tree does not 

 shrink away at the edges of the wounds as much 

 as when tar is used ; further, the new bark starts 

 into growth more quickly than when tar is the 

 antiseptic dressing applied. On cacao estates in 

 Grenada it is the custom for a boy to follow close 

 behind the pruners, and to dress all the wounds 

 made on the trees. It has been found that the 

 best means of applying these dressings is by the 

 use of a paint brush, and in most cases brushes 

 of two or three different sizes are carried, so that 

 all the holes and crevices may be readily reached. 

 In this way the dressing is neatly and quickly 

 placed on the wound and there is less likelihood 

 of any being smeared on the surrounding bark. 

 This was a point to be borne in mind when tar 

 was the material in use, since it frequently 

 burned and damaged the bark ; but no harmful 

 effects have been observed from the use of resin 

 oil. The only objection which has so far been 

 raised against the oil is that it is not easy to 

 recognise, without careful examination, which 

 wounds have been dressed, and which have not 

 yet received an application. This difficulty has 

 been got over, however, by mixing 1 part of tar 

 to 4 parts of oil. This mixture naturally pos- 

 sesses the advantages of the oil dressing, and, 

 owing to the presence of the tar, wounds which 

 have been treated can be recognised at a glance. 

 Mr Anstead states that resin oil, or the mixture 

 of oil and tar mentioned, is rapidly coming into 

 use on the large estates at Grenada in place of 

 coal tar, and has also been adopted at the Botanic 

 Station, Experiment Station, and on the Ex- 

 periment Plots. At Grenada the oil is purchased 

 in cases containing 8 1-3 gallons at £1 5s. per 

 case. It is stated that, when properly applied, 

 1 gallon of oil will go as far as 2 gallons of tar, 

 so that the former material is cheaper in the 

 end,— W.I. Agricultural News, Feb. 20. 



