1 K.WSIMKA I ION .\NI> W.NII.R SI()R.\(;i:. I 69 



could not be securetl during the time that these experiments 

 were going on. In order to compare the rate of transpira- 

 tion when the water supply is cut off, and in order to see 

 how long the lea\es of SU'Jis are able to persist under such 

 conditions, three sound leaves were removed from a plant 

 growing under favorable conditions of water supply, the cut 

 ends of their petioles were sealed with vaseline and the 

 following series of weighings were made: 



The most noticeable feature of these figures is the low 

 rate of water loss on the first few days as compared with 

 that found even in the potc^meter experiments, the average 

 for the three leaves on the first day being 69 mg. as compared 

 with the total loss of 229 mg. in the leaf on the potometer, 

 which was of nearly the same area. How much this immediate 

 checking of the rate may be due to closing of the stomata 

 and how much to other physiological controls as well, I am 

 unable to say. A second noticeable feature of the figures is 

 the fact that the daily loss of water grew less and less in 

 both absolute amount and in percentages of the total weight, 

 which is, however, no more than would be expected. 



The three leaves were lying during the entire duration 

 of the weighings on a table in the laboratory at Cinchona. 

 Returning to the experiment after an absence of several 

 weeks on the 17th of January, I found that the leaves had 

 become limber and somewhat wrinkled on the surface. In 

 order to test their capacity to reabsorb water the vaselined 



