Vol. 32 



No. 8 



BULLETIN 



OF THE 



TORREY BOTANICAL CLUB 



AUGUST, 1905 



On the transpiration of Fouquieria splendens"*" 



William Austin Cannon 



The present paper is an account of one of several studies which 

 were carried on in 1 904 by the poly meter method upon plants in 



place. It will not be necessary to give here a description of the 



method, since this will soon be done elsewhere,f but a certain 

 peculiarity attending its use may be briefly referred to. By the new 

 hygrometric method it is possible to study the transpiration of a 

 plant in the field not only once, but many times, without injury to it. 

 The fact that repeated observations of transpiration can be made 

 rendered it possible to learn not only the daily but the seasonal 

 rate as well. Thus a transpiration history, not indeed without 

 niany gaps, has been traced. The experiments were begun in 

 February and were continued from time to time until after the 

 rams oi summer were over. 



In addition to the transpiration observations, and in connection 

 with them, certain environmental factors were observed and 

 measured and a comparison was made between them and the rate 

 of transpiration. This part of the work was from necessity second- 

 ary, but despite this enough was done to establish certain impor- 

 tant facts and to indicate lines of study which may be profitably 

 followed in the fut; 



ure. 



th 



The difficulty in tracing the influence of external conditions on 

 e rate lies, among other things, in the changeableness of these 



* Papers from the Desert Botanical Laboratory of the Carnegie Institution, No. 10. 



t Cannon, W. A. A new method of measuring the transpiration of plants in place. 

 Annals of Botany, ined. 



[The Bulletin for July (32 : 337-396) was issued 29 Jl ig^S-] 



397 



