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tive period from September to February, a short resting period in 

 February, and a floral and foliar condition from February to 

 September. The yield of latex should be most abundant when the 

 trees are leafless, as they cannot then lose much water by trans- 

 piration, and it is of interest to note that the experiments made by 

 Arden in 1902 seem to give support to this view. Arden states 

 that the yield from trees tapped when they were leafless was much 

 greater than from trees tapped when the leaves were beginning to 

 appear or when in full foliage. In Nicaragua the latex from other 

 rubber trees contains the highest percentage of caoutchouc during 

 the dry season. The possession of abundance of latex during the 

 dry season lends support to the theory of its function as a water 

 store during drought. In many parts of the tropics, however, 

 the leafless period occurs when the dryness and temperature of the 

 air are at the maximum, and the collecting of latex would, during 

 such a time, be limited to the very early part of the day and the 

 evening. 



What part of the day to Tap. " The best flow of latex with the 

 minimum quantity of scrap rubber is obtained in the early morning 

 or evening on sunny days, but tapping may be clone further on 

 into the day, when the temperature is low and clouds and moisture 

 are abundant. In a district like Peradeniya the tapping may be 

 continued up to 8 or 9 a.m., and recommenced at 3 to 4 p.m. All- 

 night tapping is of course only possible when the artificial 

 lighting of estates is more perfect than at present. In the early 

 and late parts of the day the temperature is lower, the air usually 

 more moist, and there is less transpiration of water from the leaves ; 

 the combined effect of these factors is a better flow of latex dur- 

 ing such times. According to Ridley* the girth of the tree de- 

 creases during the day and increases towards evening, an obser- 

 vation which may throw some light on the theories regarding 

 tension of the laticiferous tissue and transpiration. 



Frequency of Tapping. " The frequency of tapping varies con- 

 siderably, but it is by no means clearly proved that the tree will 

 not stand tapping every alternate day throughout the greater part 

 of the year. The fact that an interval of one day is sufficient for 

 the wound response to become obvious is of interest and import- 

 ance. It is perhaps not advisable to judge the eff'ect of very 

 frequent tapping from the results obtained in the Amazon districts, 

 as there the trees are usually very old and in many cases have 

 never been tapped before. Nevertheless, it is of interest to learn 

 that in those districts, the Para rubber tree is often tapped for 180 

 days continually without apparently doing very serious damage 

 to the trees." 



Mr. R. Derry says : — " I consider the latex flows most freely 

 when the new leaves appear, which with most Hevea trees is about 

 March, and the advantage of tapping about that time is not so 

 much a question of actual yield as it is of the amount of bark 

 removed in the operation, which would be less at the best season. 



* Annual Report of the Director, Botanic Gardens, Singapore. 



