74 



REPORT OF CHEMICAL LABORATORY 



probably caused by the sudden increase in the amount of sap from which the gum is 

 produced. The increase v^'as principally in the first ten trees, which were, on the whole, 

 smaller than the rest. The amount of rain at this time was probably not sufficient to afl'ect 

 Increase in the larger trees as they did not come into leaf as a consequence. This increase, after the 

 gum a cert e g^.^j. ^.g^jj^g^ jg ^f greater interest, as it is nearly always stated that the exudation of gum 

 stops when the rain begins. It may quite probably be that more or less gum is produced 

 until the edges of the wounds caused by tapping are entirely healed up. There was 

 no sudden change of temperature for any prolonged period, nor any other exceptional 

 circumstance of any kind to account for this increased yield. The average yield from these 

 young trees is 900 grammes, considerably higher than is usually supposed to be the case. 

 From the amount exuded by individual trees, however, it will readily be seen how difficult 

 it is to reach definite conclusions from experiments with a few trees only, even though 

 these may be to all appearances under similar conditions of health, age, etc. 



YIELD OF GUM FROM SMALL TREES DURING SEASON 1908-9 (IN GRAMMES) 



This garden was much more densely covered with trees than any ordinary garden 

 which I saw belonging to the natives, which leads one to the conclusion that the amount of 



