PARA RUBBER. 71 



excellent results on a large scale on several estates in Ceylon. 

 The nature of the origin of the latex tubes in Hevea brasiliensis 

 accounts for the variation in yields from the same area ; the tubes 

 require a certain time to complete their formation, and for this 

 reason areas which do not yield any latex on particular days may 

 give abundant flows subsequently, when the processes of perforation 

 and decomposition are sufficiently advanced. 



In Java, Haas* has proved that wound response occurs in the 

 Para trees in that island. He also points out that an increase in 

 the number of incisions increases the yield of rubber, but not in 

 the same proportion, and states that an increase of 25 grammes of 

 rubber per square metre of tapped surface is only obtained after 

 more than doubling the number of incisions. 



Wound Response in 24 Hours. 

 Arden concluded from the following experiments that the length of 

 time which should elapse before re-opening incisions need only be 24 

 hours, and that tapping every alternate day instead of daily was 

 not always advisable. The following were his results : — 



60 incisions made on six consecutive days gave 99J oz. wet rubber. 

 60 ,, at intervals of twodays ,, 111 ,, ,, 



60 ,, ,, ,, ,, one week ,, 104| „ 



In the Peradeniya experiments where the spiral system has 

 been used, it has been noticed that the renewed cortical 

 tissue becomes more or less convex in outline. In some instances 

 clots of rubber were found beneath the bulging areas, and from 

 microscopic examination it was concluded that the convex outline 

 was due, to some extent, to the abnormal rapid distension of 

 the cells of the newly-formed tissue ; the coagulated rubber seemed 

 to arise by the bursting of the inflated tubes. This was " wound 

 response" to a remarkable degree, and on all such areas the use of 

 Bowman's and Northway's pricking instrument gave abundant 

 Hows of latex. 



There is a certain amount of reason in tapping any yielding area of 

 the stem and branches, on account of the peculiar manner in which 

 the latex tubes are produced and their connection with one another. 

 The tubes in Para rubber are produced by the breaking down of the 

 partition walls of adjacent cells or sacs, and the final tubes may 

 be very short or long according to the age and the number of par- 

 tition walls which have been dissolved. The tubes arise de novo, 

 and in tapping operations one does not necessarily drain the latex 

 from all parts of the tree, but very often only from one or two inches 

 around the incision, where latex tubes have been formed. 



* Results of experimental tappings of Hevea brasiliensis, Java, 1900- 

 1904, by Dr. W. R. Tromp de Haas. (Vide Bulletin of Straits & F. M. S. . 

 August, 1905. 



