THE CEARA RUBBER TREE 



156 



and tlic smallest 23- 6 in. The trees were divided into 

 thiiteen groups, which were tapped in different ways by 

 the spiral, herringbone, and pricking systems, the incisions 

 in the first two methods being reopened every second or 

 fom-th day. The experiments lasted about one month, 

 and the number of tappings varied from six to tlm-tcen 

 in the different groups. The average yield of dry rubber 

 per tree was 112-5 grams {3-97 oz.), made up of biscuit 

 and scrap in nearly equal proportions. 



Southern Nigeria. — Tapping experiments have been 

 conducted on Ceara trees growing at Calabar and Onitsha 

 in Southern Nigeria. The trees were tapped eight times 

 during a period of two and a half months by Johnson's 

 method (see p. 149), and fmiiislied the folio wmg results : 



The yield from the trees at Calabar was very good, 

 amounting to 8 oz. and 3' 57 oz. per tree in the two groups 

 for two and a half months' tapping. The trees at Onitsha 

 gave much less rubber, possibly OAving to the facts that 

 they have been neglected and that the rainfcxll at that 

 place is much less than at Calabar. 



Belgian Congo. — The following table summarises 

 the results of a number of tapping experiments made on 

 Ceara trees in the Belgian Congo : 



