RUBBER PLANTING 47 



Flemmings solution, the contents of the cells which 

 are about to form the latex vessels are distinguishable 

 almost immediately after they have been cut off from 

 the cambium (Fig. n). Their appearance and arrange- 

 ment at this stage is closely comparable with that of the 

 companion cells of the phloem. * Sometimes the nuclei 

 of the surrounding larger cells are to be observed closely 

 pressed against the walls next to the incipient latex 

 vessels, suggesting that the former may play some part 

 in providing materials for the contents of the latter. 

 The adult bark of Manihot has not been so closely 

 studied as that of Hevea, but the manner of formation of 

 the vessels appears to be closely similar in the two 

 cases. For further details, and for a full account of the 

 structure of the laticiferous system in the seedling, the 

 reader is referred to the papers of Dr D. H. Scott. 



The effects of wounding tJte bark. 



The further remarks in this and the following chapter 

 refer specially to Hevea brasiliensis unless otherwise 

 stated, for this is the only species of which the physio- 

 logy has been at all adequately studied. Even in the 

 case of Hevea further observations are much needed, 

 especially from the chemical side. 



The evil effects of ringing the bark, i.e. severing it 

 by a cut which penetrates to the cambium and extends 

 right round the trunk, are primarily due to the inter- 

 ruption of the downward food current. Their food 



