

if 



&\ 







THE RELATION OF TRANSPIRATION AND STOMATAL 

 MOVEMENTS TO THE WATER-CONTENT OF THE 

 LEAVES IN FOUQUIERIA SPLENDEXS 1 



FRANCIS E. LLOYD 



Alabama Polytechnic Institute, Auburn, Alabama 



In a previous paper 2 1 stated that the error due to the use of the 

 potometer in studying transpiration in Fouquieria splendens, 

 as indicated by comparative weighings, fell for a total of twenty- 

 four hours below a maximum of 4 per cent, and that this error was 

 so distributed as not to affect the general character of the curve 

 of transpiration rates. This outcome of my control experiments 

 at that time was the sole consideration, and I did not, therefore, 

 examine any further into the possible meaning of the discrepan- 

 cies noted. 3 It was, however, obvious that there must be some 

 proper explanation of them. Either they must have been due 

 to accidental circumstances, such as possible temporary obstruc- 

 tions in the path of the water current in the stem or the wilting 

 of the leaves; or they must represent some changing ratio, due to 

 normal causes, between the water received by the leaf and that 

 exhaled by it. I had previously excluded, to my own satisfac- 

 tion, the possibility of plugging at the cut end of the stem, by a 

 simple method already described in my paper cited above. A 

 reexamination of a part of the data there published indicates that 

 the latter alternative is more likely correct, from the fact that 

 water was retained by the plant during the night, while the reverse 

 occurred in the daytime. This result might have been ascribed 

 to the behavior of the stomata, or to some other cause, but any 



1 Read by title at the annual meeting of the Botanical Society of America, 

 Minneapolis, Minn., December, 1910. Digest in Science, n. s., 33: 191. 3 Feb., 

 1911. Ref. in Expt. Sta. Record 25: 124. Aug., 1911. 



2 The Physiology of Stomata. Carn. Inst. Wash., Publ. 82. 



3 Lloyd, I. c, p. 20. 



THE PLANT WORLD, VOL. 15, XO. 1, JANUARY, 1912 



1 



