414 



BOTANICAL GAZETTE 



[DECEMBER 



record was kept of the time of the fall of each leaf, together with its 

 area. 



The transpiration graphs show a general falling off after 

 October ii, which is not unlike that of the conifers; only here the 

 transpiration is from a constantly decreasing area (all the leaves 

 had fallen or remaining fragments were removed by October 26), 

 while in the conifers the area remains constant. In table VI are 

 given the total losses (which are too small to plot on an average 

 daily basis) from October 26 to May i. 



TABLE VI 



TOXAL LOSSES (iN GM.) FROM 12 ELM TREES FROM OCTOBER 26 TO MaY I 



From November 9 to 23 the seals were removed and the soil 

 allowed to dry out. The loss was about 125-175 gm. They were 

 then resealed, and 250 cc. of water was added. On April 24 some 

 of the plants, as nos. 2, 10, and 11, had buds swollen but not yet 

 open, while in others, as nos. 3, 6, and 7, the leaves were unfolding. 

 On May i nos. 3 and 6 had leaves fairly well out, some of them 

 being over i . 5 cm. long, while in others (as nos. i and 7) the leaves 

 were just bursting from the buds. 



The winter losses are very small. During a period of 42 days 

 (November 23 to January 4) the average loss was only i gm. from 

 the bare stems which exposed an area of 0.28 to o . 50 sq. dm. 

 Table IX gives the relative transpiration losses of conifers and 

 broad-leaved trees. 



