404 



BOTANICAL GAZETTE 



[DECEMBER 



actual losses are generally correlated with the leaf area ; for example, 

 the greatest losses are from plant no. 7 with an area of 4 .47 sq. dm., 

 while those in graph no. 2 are from a plant with an area of only 

 2 . 14 sq. dm. Secondly, there may be noted a rise or fall in the 

 graphs which corresponds in general with temperature changes. 

 After October 1 7 there was a gradual but marked falling off in water 



Fig. 4. — Battery of 3-year-old jack pines 



losses, and the rate remained very low until about the first week in 

 April, when growth was resumed. These data are shown in 

 table IV. 



TABLE IV 



Total transpiration losses (in gm.) from 3-year-old jack pines during the 



SEVERAL intervals FROM DECEMBER 1 9 TO ApRIL 29 



