72 THE WHOLE ART OF RUBBER-GROWING 



A tree fifteen months old gave 5 oz. of rubber. Many 

 other trees were subjected to similar trials with like 

 results. In all cases the large V cut, which Central 

 Americans invariably apply to all their rubber trees 

 irrespective of species, was used, and the latex col- 

 lected as scrap in the manner familiar to the sering- 

 hals of Brazil. 



The average rate of growth of the Manihot 

 Glaziovii is well illustrated by the following table of 

 a return provided by the Ceylon authorities some 

 time ago. The rate of growth and development is 

 for the first five years. 



Age. Height. Trunk to Branch. Circumference. 



\ } 18 feet ... 8 feet { finches 



3 -. 35 9 ... 291 I! 



4 ... 42 ,, ... ii ,, ... 41^ ,, 



5 -.- 50 ,, -.- 22 ,, ... 45! 



In a general way tapping of this tree commences 

 when it is 22 inches in circumference. A refer- 

 ence to the above table shows that this measure- 

 ment was attained when the trees were just two 

 years old. 



The botanical points of the Manihot are sharply 

 defined and therefore readily distinguished from those 

 of any other rubber tree. It is of moderate size, 

 from 30 feet to 58 feet high and 8 inches to 24 inches 

 in diameter. The leaves are palmate, cut somewhat 

 deeply into three, five or seven oblongovate lobes, 

 smooth on both surfaces, thin in texture, deep bluish- 

 green above and light beneath. The flowers are 

 large, unisexual and very numerous. The fruit is a 



