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SCIENCE PROGRESS 



lents were consequently above that of the test solution, were 

 placed in fresh or slightly saline water for some time, at the 

 conclusion of which the average osmotic equivalents were 

 determined. In each case they were found to be very much 

 lower (Table III). 



Table III 



These results were confirmed b}^ various other tests, and 

 clearly show that the root-hairs of Salicomia, growing in places 

 where the soil-water is strongly saline, can accommodate their 

 internal osmotic pressure as the salinity of the soil-water falls 

 in concentration. 



It remains to be ascertained whether or not they are cap- 

 able of raising their internal osmotic strength in proportion 

 to the increase of the external salinity. 



Sods containing seedlings of Salicomia were taken from a 

 spot which had been covered by the tide a few hours before, 

 and placed in a dish of fresh water which was changed at in- 

 tervals in order to reduce gradually the salinity. Periodically 

 seedlings were tested with regard to the osmotic strength of 

 the cell-sap of the root-hairs. The strength of the sodium 

 chloride solution used for the test was 3-5 per cent. 



Eventually the root- hairs of a number of seedlings were 

 found to be strongly plasmolysed by this solution. These were 

 allowed to remain in a saline bath of the test solution all night ; 

 the next morning 81 per cent, showed no plasmolysis, and 

 19 per cent, were slightly plasmolysed, but nothing like to so 

 great an extent as" when they were first examined. These 

 results were confirmed by removing a portion of the sod from 

 the bath of fresh water and placing it in a bath of 3*5 per cent, 

 sodium chloride. Natural conditions were thus reproduced, 

 and all the seedlings examined behaved as before. 



A fresh batch of seedlings were then taken from the turf 

 soaked in fresh water, and drawings were made of the roots, 

 in order that the root-hairs could be identified when micro- 

 scopically examined after subsequent treatment. To start 



