315 



tip of the plumule is held between the cotyledons in the seed 

 and comes out between the two stalks of the cotyledons, a 

 figure is given of this. One plant growing thus got an excess 

 of water and the loop swelling too much, the tip broke off. 

 The plumule had thus no growing point. Headless seed- 

 lings he says are not uncommon in nurseries. They then 

 produce two buds from the axils of the cotyledons and a 

 double stemmed plant is the result. The paper is illustrat- 

 ed by photographs of abnormal and normal seedlings. 



Burrs. The second circular deals with the subject of 

 Burrs, of which the author distinguishes two forms. 

 Wound burrs and burrs formed by nodules. The first is 

 due to the injury of the wood in tapping, or otherwise. 

 At the edge of any wound the cambium produces a swollen 

 cushion of new wood and bark, and this wood is of a distinct 

 structure from normal wood and is known as wound wood. 

 The amount produced is greater at the point where the cam- 

 bium is injured than would be the case where it is not in- 

 jured consequently the wounded part is elevated and the 

 pattern of the wood raised. In a short time the cam- 

 bium produces normal wood instead of wound wood 

 and theoretically the gradual growth of the wood should 

 obliterate the pattern, but this appears to be a slow 

 process in Hevea. (Strictly speaking these elevated 

 portions of wood and bark produced in wound re- 

 pair should not be called burrs but perhaps wound-scars 

 would be a better word). The burrs caused by nodules, are 

 what are usually known as burrs. The structure and his- 

 tory of these is fully described. They are very troublesome 

 if they develope to any great extent on the trunk for the 

 bark over them often dries up and no latex can be got, as the 

 only laticiferous tissue lies behind the burr. The author 

 urges the excision of the core of the burr before it attains 

 any considerable size. ''If the outside of the burr is sliced 

 off the core can be shelled out quite easily but if they are 

 allowed to grow they become attached to the main wood at 

 several points and a very ugly wound results when an 

 attempt is made to cut them out." 



The main source of such burrs lies in the use of the 

 pricker, according to the author and this seems to be suffi- 

 ciently well proved. An improved pricker has been in- 

 vented which is said not to produce burrs, but it is too soon 

 to prove this, and theoretically at least the new one which is 

 blunt should prove more injurious than the old one. 



It would be better probably to abolish the pricker al- 

 together. 



