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BULLETIN 229. U. S. DEPARTMENT OF AGRICULTURE. 



tions the flow increased or decreased with increase or decrease of tem- 

 perature. The effect of cool weather in checking the flow is especially 

 marked toward the end of the season. 



FIG. 10. Comparison of flow from north and south faces of each of fifty trees. 

 RATE OF FLOW DURING WEEK. 



Data on the variation in rate of flow were secured by weighing the 

 north and south cups on 10 trees on the third day after each chipping 

 throughout the season. The sum of the weights for each tree was 

 compared with the weight of the total flow for the season from the 



3 10 16 23 30 7 14 21 28 4 II 18 25 I 8 15 22 29 6 13 20 27 3 

 JUN. JUL. AUG. SEP. OCT. NOV. 



TIG. 11. Relation between temperature and rate of flow of gum. 



same trees. An average of the results shows that 73 per cent of the 

 weekly flow occurred in the first three days. This ratio varied from 

 65 per cent to 78,6 per cent in the 10 test trees. 



