194 THE AFRICAN RUBBER VINES 



before winding the strips into balls. In certain districts 

 the strips of rubber are made into cylinchical or spindle- 

 shaped roUs, instead of into balls. 



This method of collecting the rubber is adopted in the 

 case of L. Heudelotii, L. owariensis, and L. Kirkii. 



(2) By collecting the latex in hulk and subsequently 

 coagulating it. — This method is, of course, only applicable 

 to those vines which yield their latex freely when in- 

 cisions are made in the stems. 



As in the preceding case, the natives either tap the 

 standing vines or first pull the main stems down from 

 the supporting tree and lay them along the ground. 

 Numerous incisions are made in the stems, the latex beincr 

 collected in cups made from leaves or in receptacles of 

 some other kind and subsequently coagulated. A 

 quantity of scrap rubber can afterwards be collected from 

 the incisions. 



Another plan which is adopted in some districts consists 

 in severing the main stem of the vine a short distance 

 above the ground and pulling the vine down from the 

 tree as completely as possible. The stems are then cut 

 into short pieces about 12 in. in length, which are placed 

 upright in a trough and the latex allowed to drain from 

 them as completely as possible. The small quantity of 

 rubber which coagulates on the cut ends of the stems is 

 subsequently collected, and sometimes the rubber left 

 in the bark after the above treatment is extracted by the 

 process of beating described on p. 195, 



The latex collected in bulk by any of the.o methods 

 is coagulated in a variety of ways, the principal of which 

 are the following : 



(a) By heat. — The latex may be coagulated in many 

 cases by the application of heat, either by boiling the 

 latex, by immersing the vessel contaming it in boiling 

 water, or by pouring the latex into boiling water. If the 

 latex is coagulated by the application of direct lieat, 

 great care should be taken to avoid over-heating the 

 rubber, and the other two methods, when effective, are to 

 be preferred, as they obviate this danger. 



The latex of Clitandra orientalis, and also of C. Arnold- 

 iarm and C. elastica,, is readily coagulated by boiling. 



{h) By the addition of various coagulants. — The coagu- 

 lants pruicipally used by the natives for the latex of 



