THE CENTRAL AMERICAN RUBBER TREE 223 



The results for the trees eight and eleven years old are 

 the means of a number of experiments, whilst the figures 

 for the younger trees are the means of two trials. The 

 results were considered to be rather below than above 

 the average. Weber stated that the trees can be tapped 

 safely twice a year, so that the annual yield of rubber 

 would be double the above amounts. 



Trinidad and Tobago. — (1) The Trinidad Depart- 

 ment of Agriculture has published the results of experi- 

 ments conducted on 200 Castilloa trees, which had not 

 been previously tapped, growing on the Lure Estate, 

 Tobago. Twenty of the trees were fourteen years old 

 and from 60 to 86 in. in girth, whilst the remainder were 

 ten years old and under, the majority of them ranging 

 from 40 to 70 in. in girth. The trees were tapped by 

 Smith's method to a height of about 20 ft. 



The first series of experiments was conducted from 

 April 6 to May 18, 1911, and an average yield of 5* 12 oz. 

 of dry rubber per tree was obtained. The trees were 

 tapped a second time, using the same method, from 

 August 7 to September 15, 1911, and furnished a further 

 yield of 3" 37 oz. of dry rubber per tree, making a total 

 of 85 oz. per tree in the two tappings. 



(2) The results of tapping 24,000 Castilloa trees, ten 

 to twelve years old, in Tobago have been recorded by 

 Smith. The trees were tapped three times during the year 

 to a height of 6 ft. and furnished an average yield of 

 2| oz. of dry rubber per tree. In the case of three groups 

 of trees he also gives the yield from the first tapping, 

 which is usually greater than that obtained from the 

 subsequent tappmgs. : 



(3) Thirteen trees, eight to nine years old and from 

 33 to 69 in. in girth, were tapped to a height of 6 ft. by 

 Smith's system, two tappings being made at an interval 



