40 4 SCIENCE PROGRESS 



Now that plant-breeding has almost become an exact science, 

 largely through the application of the principles of Mendelism, 

 comparatively quick results might be obtained even with a 

 tropical tree. In ten to fifteen years' time seeds of a valuable 

 strain might be forthcoming with which estates could replace 

 worn-out trees or plant additional ground. The writer has 

 referred in greater detail to this matter in a recent article. 1 



The Extraction of the Latex 



The procedure employed in the East for the extraction of 

 the latex from the stems of cultivated Hevea trees was elabo- 

 rated independently, and not influenced by the native method 

 still used in the forests of the Amazon. 



The late Dr. Trimen in 1888 commenced tapping experi- 

 ments at Henaratgoda in Ceylon on the rubber trees which 

 had grown from the seedlings received from Kew in 1876. 

 Vertical rows of V-shaped incisions were made in the bark 

 of the trunk, from a height of six feet downwards, with a 

 mallet and carpenter's chisel. The incisions were placed about 

 a foot apart vertically, and the rows at a like distance hori- 

 zontally. The latex oozing out of these cuts was made to 

 trickle down the surface of the bark in a series of streams 

 corresponding to the number of vertical rows of incisions. 

 The whole of the milk was caught at the base by a clay gutter 

 moulded round the trunk, and directed into one or more 

 coco-nut shells placed around the foot of the tree. A second 

 tapping was performed in a similar manner, the new incisions 

 being inserted between the old ones, and so for subsequent 

 bleedings. For details of this somewhat crude method, now 

 almost obsolete, the reader is referred to one of the circulars 

 published by the Ceylon Botanic Gardens Department. 2 



Dr. Willis continued the tapping experiments initiated by 

 his predecessor, employing the same method. His results 

 with respect to yield of rubber per single tapping brought 

 out the remarkable fact that the second tapping gives a con- 

 siderably larger quantity of caoutchouc than the first. Since 

 his figures gave the first indication of the now well-known 



1 J. Parkin, India- Rubber Journal (Quarter-century No.), 1909, p. 63. 



'' Willis, Circular, Roy. Rot. Gardens, Ceylon, 1898, No. 4, Series I. 30-31. 



