J.ANDOIJMIIA Kl'HHER FORESTS 103 



new shoots from the stumps of cut vines to 

 some extent. Mr. Diiwe, the Director of Agri- 

 culture of the Mozambique Comptany, found that 

 on the Madanda forest the general average of 

 the number of vines C centimetres and over 

 in circumference per hectare in the rubber- 

 bearing area worked out at eighty. The average 

 number of vines required to produce 1 kilo 

 of rubber is not known, I think, but there are 

 data upon which an estimate can be made of 

 the return per hectare. For instance, in the 

 experiment I made at Matadane, described above, 

 the weight of wet rubber was 3 per cent, of that 

 of the wet roots ; we may assume, therefore, 

 that 100 kilos of dry roots would yield 3 kilos of 

 dry rubber. Vines, of course, vary enormously 

 in size. ]Mr. Dawe noted one varying in cir- 

 cumference from 18 to 62 centimetres, which 

 carried approximately 1-30 metres of tappable 

 branches, but for this rather dry part of Africa 

 the average would be much less than this. 

 One metre of dry Landolphia rubber stem 

 9 centimetres in circumference weighs 417 

 grammes. Taking the average circumference of 

 tappable vines at a little larger than this, we 

 may reckon a piece of dry stem 2 metres in 

 length weighs 1 kilo, and that an average 

 plant carries 20 metres of tappable branches. 



