1915-16.J BOTANICAL SOCIETY OF EDINBURGH 59 



stricta as a Scottish species ; but an examination of fifty- 

 two specimens of .sco^/ca, among them a third from Orkney, 

 from Mr. Spence, and a specimen of the variety itself, 

 hardly sustains the idea of stricta. 



Twice the length of the calyx is certainly very unusual, 

 but half as long again occurs in many ; and stricta is a 

 taller, more gracile species, with the leaves " subtus 

 nudiusculis," not " subtus farinosis," as in scotica. It 

 seems to be better to adopt Dr. Moss's name of var. 

 orkniensis for the plant. 



To the bibliography should be added Low's list of 

 Orkney plants in Barry's History : — 



1. A second edition in 1808, by Rev. J. Hendrick. 



2. Another in 1813, edited by W. E. Leach. 



3. Syme in Bot. Soc. Edin. iv, 47-50 (1850). 



4. Col. Johnston in Trans. Bot. Soc. Edin., xxvi, 207-226 

 (1914). 



There are still about fifty species reported in various 

 lists, etc., that have not been confirmed, and are probably 

 mostly errors. 



Periodicity in Transpiration. By Sophie 

 J. WiLKiE, B.Sc. (Two figures.) 



(Rea<l 14th October 1915.) 



Periodicity in transpiration has been recorded by various 

 research workers, and the evidences up to 1904 have been 

 collected by Burgerstein in his monograph Die Transpira- 

 tion der Pflanzen (Jena, Verlag von Gustav Fischer, 1904). 

 A daily maximum has been obtained, and was found to 

 occur any time between the hours of 9 a.m. and 3 p.m., vary- 

 ing with the different species of twigs experimented upon. 



Linger (Sitzb. d. k. Akad. der Wissensch. Wien, Bd. xliv, 

 1862, pp. 181-327) was the first to accept this periodicity, 

 but his experiments were not performed under constant 

 conditions. 



Sachs (Landw. Vers. Stationem, Bd. i, 1859, p. 203) 

 believed in the rhythm of transpiration on analogy with 

 growth periodicity. 



