RUBBER PLANTING 85 



as well as upon the supply of moisture, since otherwise 

 the concentration might be expected to be highest in 

 the dry season and lowest in the wet. There is however 

 no evidence of an increase in concentration during dry 

 weather. 



The concentrations here recorded were determined 

 by dividing the weight of dry rubber by the volume of 

 the latex, a method which gives values slightly too low 

 throughout. 



The dry rubber obtained in this experiment from the 

 second to the sixth tapping of each group (samples A), 

 and again after tapping had been in progress for four 

 months (samples B) was analysed for ash, resin and 

 organic matter. As regards ash, practically no differ- 

 ence was found between the product of earlier and 

 later tappings. The proportion of resin showed a slight 

 falling off in the product of the later tappings, especially 

 in the case of the more frequent intervals. 



The organic matter in the two series showed 

 differences of considerable interest. In the groups 

 tapped at shorter intervals the organic matter from the 

 later tappings showed a distinct increase, whilst in the 

 groups tapped at longer intervals the reverse was 

 the case. The following purely tentative explanation 

 was put forward to explain these differences. "If we 

 suppose that some part of this organic matter represents 

 the raw material from which the rubber is formed, then, 

 in the case of daily tapping we may suppose that the 

 drain upon the resources of the tree is at first greater 



