ARTICLES 



THE WATER ECONOMY OF MARITIME 



PLANTS 



By T. G. HILL, A.R.C.S., F.L.S., 



University College, London 



Since 1904 particular attention has been given by the botanical 

 department of University College, London, to the problems 

 associated with the conditions of existence of maritime plants. 

 The investigations alluded to were initiated at Erquy on the 

 coast of Brittany, and were continued at Blakeney in Norfolk 

 and in the departmental laboratories. Amongst the results 

 obtained is a certain amount of information regarding the 

 absorption and transpiration of water by halophilous plants, 

 more particularly by such characteristic forms as Salicornia 

 and Suceda. 



In the present article an attempt is made to weave into a 

 consecutive story the results already made public together 

 with certain unpublished observations ; attention to other 

 work is given only so far as is considered necessary. 



THE ACTION OF SODIUM CHLORIDE 



Sodium chloride being an all-important factor in the con- 

 figuration of a salt-marsh vegetation, attention may first be 

 directed to certain effects of this substance on plants. 



The work of several investigators has shown that a solution 

 of pure sodium chloride has a pronounced toxic effect upon 

 plants ; and this is true not only for ordinary mesophytes, but 

 also for marine plants. If, however, other salts be dissolved 

 in the salt solution, the solution, although it contains as much 

 sodium chloride as before, does not have any such ill-effect. 



Under natural conditions, plants are not subjected to the 



action of pure solutions, and if sodium chloride be present in 



the soil, there also are present other salts which exert a pro- 



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