198 



THE AFRICAN RUBBER VINES 



ten years, and the following yields of rubber were ob- 

 tained : 



No. 1 

 2 

 3 

 4 



The total yield of rubber from the eight vmes was 

 232' 5 grams, an average of 29 grams per vine. The 

 vmes are tapped three times a year by the natives ; and 

 if the average yield obtained in the experiments was 

 normal, it would correspond to an average annual yield 

 of about 87 grams per vine. 



Later trials made at the experimental garden at 

 Camayenne have shown that 100 to 150 grams of rubber 

 per annum can be regularly obtamed in two tappings 

 from L. Heudelotii vines when ten to twelve years old ; 

 and Yves Henry, the Inspector of Agriculture in French 

 West Africa, has expressed the opinion that eight-year- 

 old vines growing under the best conditions will yield 

 at least 200 grams of rubber per annum. 



All these yields of rubber from Landolphia Heudelotii 

 were obtained by tapping methods only. 



Landolphia oivariensis. — A number of experiments to 

 determine the yield of rubber from vines of this species 

 have been made in the Belgian Congo, the rubber bemg 

 first extracted by tapping or by cutting the stems into 

 short lengths, and subsequently by beatmg the dried 

 bark. 



From a vine seven years old Cranshoff obtained the 

 following results : 



Yield of rubber, 

 grams. 



Tapping of oldest stems and primary branches 18 



Beating of bark from tapped stems . . 37 



„ ,, ,, untapped stems . . 8 



