THE AFRICAN RUBBER VINES 



203 



Another experiment was conducted with a large forest 

 vine, using both stems and roots. The principal stem 

 was 17^ metres long and from 30 to 25 cm. in circum- 

 ference ; the branches were 106 1 metres in length and 

 from 20 to 4 cm. in circumference ; the root was 9 metres 

 long and from 25 to 7 cm. in circumference. This vine 

 was treated in the following manner : (1) all the parts 

 were cut into pieces from 12 to 20 in. long and the latex 

 allowed to drain out ; (2) two days afterwards about 

 4 in. was cut from the larger end of each piece, when a 

 fresh flow of latex was obtained ; (3) two days lat^r a 

 circular incision was made in the middle of each piece. 

 The following yields of latex and rubber were obtained : 



The total yield of fresh rubber was therefore 851 grams, 

 and this furnished 720 grams of dry rubber. No rubber 

 was obtained by beatmg the bark. 



It would appear from these experiments that the latex 

 of Clitandra Arnoldiana, unlike that of Landolphia 

 owariensis, drains almost completely from the cut stems, 

 and that practically no rubber can be subsequently 

 obtained by beating the bark. 



It may be mentioned that four of the five vines used 

 in the first experiments were found to be dead about 

 two months after being cut ; the fifth had developed 

 some new shoots, but not from the cut stem, but from 

 some small branches which had been left intact. 



The results of an experiment to determine the yield 

 of rubber obtainable from Clitandra Arnoldiana by 

 tapping may also be given. At the first tapping the 

 vine furnished 270 cc. of latex, which yielded 100 grams 



