igig] 



WEAVER &- MOGENSEN— TRANSPIRATION 



407 



Since weighings of both sets of firs were taken on the same days, 

 the graphs in fig. 6 may be compared directly with those in fig. 8. 



Fig. 7. — Battery of 4-year-old white firs; photographed February 28, 1918, 

 after some of leaves had fallen. 



W 



r^f'^^i 



:m 





il. 





Q_ 



Fig. 8. — Average daily losses in grams from battery of seven 4-year-old white 

 firs; September 28 to December 19, 191 7. 



A marked irregularity in the course of the otherwise generally 

 parallel graphs may be seen during the period of October 23 to 

 November 16. 



