Spalding: Absorption of atmospheric moisture 



371 



few centimeters in length, with their terminal buds, were employed. 

 Table II shows that these shoots gained appreciably in weight in 

 a nearly saturated atmosphere, but rapidly lost more than they had 

 gained when left in an atmosphere the relative humidity of which 

 was registered at 45 and upwards. The experiment was varied 

 by covering the buds of another shoot with vaseline and leaving 

 those of a control shoot untouched. As shown by Table III, the 

 former shoot gained in weight nearly two thirds as much as the 

 control, thus indicating that although the buds share in the process 

 they are not the chief absorbing structure. 



Table III. Fouquieria splendens. November 14-15, 1905. 



No. 



3 



Time. 



IO.48A.M. 



4 I 10.54 



3 



4 



2.05 P.M. 



2.10 



Weight. 



5-643^ 

 6.406 



5-655 

 6.425 



Loss or Gain. 



3 



4 



3 

 4 



2.30 



0.012 



0.019 



3 



4 



2-33 

 Nov. 



10.09 

 10.14 



J 5- 



5.650 

 6.417 



12.46 P.M 



12. ;o 



Gain. 



Conditions. 



t < 



0.005 Loss 



0.008 



<t 



5.618 0.032 Loss 



6-3 6 5 

 5.629 



6.380 



0.052 



it 



O.OII 



0.015 



Gain 





Weighed soon after cutting. 

 Weighed soon after cutting. 



■ 



After exposure to nearly saturated at 

 mosphere. 



After exposure to nearly saturated at 

 mosphere. 



After exposure to air of laboratory. Re- 

 corded relative humidity = 44 per cent 



After exposure to air of laboratory. Re 

 corded relative humidity = 44 per cent 



After exposure to air of laboratory. 

 After exposure to air of laboratory. 



After exposure to nearly saturated at- 

 mosphere. 



After exposure to nearly saturated at- 

 mosphere. 



But, notwithstanding the fact, thus fully established, that the 

 shoots of Fouquieria absorb considerable quantities of water vapor 

 from a saturated atmosphere, it seems entirely unlikely that in 

 nature the leaves receive from the branches any appreciable amount 

 of water as a result. One morning with the recording hygrometer 



registering the humidity at 72, the branches lost rapidly a large 

 percentage of what they had gained over night in a nearly satu- 

 rated atmosphere, and this was the usual, rather than exceptional, 

 state of affairs ; so that the rapidity with which the branches re- 

 turn to the air the water they have absorbed, even when the 

 humidity is high, seems to preclude the assumption that any, or 

 at least any considerable amount, is passed on by them to the leaves. 



