On a Method of Studying Transpiration. 



275 



is to say, a relatively slow response to the change in the humidity of the 

 air (yfr). When the air is drying instead of becoming damper the " lag " is of 

 the opposite character, as seen in fig. 6. 



Experiment 3. — November 15, 1909. P. laurocerasus. Fig. 3. 



Time. 



Period. 



Rate. 



T. 











° C. 



per cent. 



11.30 A.M. 1 



12.6 p.m. J 



i 



57-0 



15-4 



54 



12.12 „ 



Bell over plant. 







12.19 „ 1 

 12.44 „ J 



ii 



50 -0 



15 4 



60 



2.54 „ \ 

 3.19 „ J 



iii 



23 5 



15-4 



83 



3.28 „ 



Water poured on floor of bell. 





3.44 „ 1 







15 5 



94 



3.56 „ J 



V 



13 



3.56 „ 1 









94 



4.10 „ J 



vi 



11 



15-4 



60 





50 





40 





30 





20 





10 





, / 



1 . . , , 



Fig. 3 (Experiment 3). 



Experiment 4. — January 1, 1910. P. laurocerasus. Fig. 4. 



Time. 



• Period. 



Eate. 



T. 











°C. 



per cent. 



12.35 p.m. 



i 



42 -7 



14 -4 



53 



12.51 „ 



Bell-iar on. 







12.59 „ 



ii 



37 -9 



14 -6 



63 



2.30 „ 



iii 



33 3 



14 -2 



61 



3.12 „ 



iv 



30 -7 



14 -7 



68 



3.22 „ 



V 



25 -8 



14 -8 



72 



3.35 „ 



vi 



22 -6 



14 -7 



77 



3.47 „ 



vii 



19-2 



14 -7 



81 



4.4 „ 



viii 



16 -1 



14 -9 



89 



