EXPEEIMENTS ON GUM PRODUCTION IN KORDOFAN 



79 



in their yield of gum under ordinary circumstances, even though to all appearance they 

 are under similar conditions of health and size, and thougli they are sufficiently infected to 

 produce a considerable quantity of gum. 



With a view to supplementing Dr. Beam's experiments in this direction I treated a 

 number of trees both before and after tapping witli a number of solutions, and observed the 

 effect of this on the exudation of gum. The trees chosen for this purpose were young trees 

 never previously tapped, in the garden already described. They were nearly uniform in 

 size, neither the smallest nor the largest being used. To make the results more comparable Experimems 

 also, the trees were not tapped heavily, as would be the case if a large yield of gum was 



desired, but a strip of bark about 30 inches long by an inch and a half wide was removed 

 in each case. 



It was thought that treatment of the wound with strong antiseptics such as formalin 

 and mercuric chloride would, by killing the bacteria, prevent the exudation of gum. At 

 Dr. Beam's suggestion I also treated the bark of a number of trees with the same solutions 

 before tapping, with a view to finding whether killing the bacteria on the outside of, or 

 near the surface of, the bark would have the effect of preventing the formation of any gum. 



with 

 antiseptics 



In testing the effect of each solution used, six trees were employed. In those cases 

 where the tree was to receive preliminary treatment, the bark where tapping was to take 

 place was thoroughly rubbed with cotton wool saturated with the solution used, on each 

 of the three days preceding the tapping. In the otlier cases the wdimdcd surface was 

 rubbed with the solution immediately before tapping and also on the two succeeding days. 

 It was hoped that the whole wound would thus be thoroughly impregnated with the 

 substance in question. 



The trees of which the bark had previously been treated were tapped on November 19 

 and the others on the next day, the temperature on both of these days being about the 

 same, and not too low. 



