COLLECTING THE LATEX. 77 



It is therefore evident that an incision should reach this portion, 

 in order to secure a good supply of latex ; but it should not 

 penetrate to the wood of the tree, as such a wound takes a long 

 time to heal, and serious damage to the health of the tree is 

 likely to accrue. 



The laticifers traverse the bark principally in a longitudinal 

 direction, and with very little lateral communication, so that a 

 transverse incision will tap more vessels than a longitudinal one. 

 Latex is, however, more easily collected from an oblique cut 

 than from a horizontal one, as from the latter it tends to flow 

 over on the bark at more than one point, and some is liable to 

 be wasted ; whereas, it is an easy matter to collect latex flowing 

 from an oblique cut by fastening a collecting vessel at the lowest 

 point. 



The best time of the day to tap likewise requires considera- 

 tion, as the flow of latex varies considerably during different 

 periods of the day. In practice, it has been proved that the 

 flow of latex is most copious during the early morning and in 

 the evening, a fact accounted for by some observers by the effect 

 of the sun's heat on the latex. 



It is, however, probably due more to the fact that the tension 

 of the plant's tissues varies at different periods of the day, and 

 corresponds to the quantity of water being transpired by the 

 plant. 



Transpiration is at its maximum during the early portion of 

 the afternoon, and tension is thereby lessened by the diminishing 

 of the water in the plant vessels ; consequently the flow of latex 

 is much slower at this time of day. 



Transpiration diminishes during the evening, and the flow of 

 latex is then more abundant, but is, as one would naturally infer, 

 still more abundant at daybreak. 



In the Amazon valley, the native collectors never tap the trees 

 when they are in flower, giving as a reason that the amount of 

 rubber then obtainable is much less than at other times ; and 

 this curious phenomenon has been proved to obtain in the trees 

 cultivated in the Botanic Gardens, Singapore. 



The flow of latex is more abundant during wet weather than 

 in dry, and a heavy shower of rain will materially affect the latex 

 flow on two successive days. 



As previously pointed out, the object to aim at in tapping is 



