1909.] Coverings of the Seeds of Hordeum vulgare. 87 



Table II. 



Solute. 



Percentage of water absorbed after steepin 



1 the seeds during — 



2 days. 



4 days. 



6 days. 



8 days. 



11 days. 



KC1 



31-2 



36 -5 



36 -9 





37 -3 



38 -4 



NaCl 



30 -5 



34 -2 



35 7 





37 "3 



37-2 



NH.C1 



31 -7 



34-6 



36 "4 





36 -6 



37 -4 



KNO, 



34-1 



38 -7 



40-5 





41 -1 



41 -6 



NaNO, 



32 -5 



36 -3 



37 -5 





38 -7 



38 -5 



NH 4 NO, 



32 -3 



36 -1 



38 -3 





38 -4 



38 -9 



Water (control) 



43 -1 



55-6 



64-1 





68 -3 



70 -0 



active in the case both of the chloride and nitrate than either the sodium or 

 ammonium salt, which behave alike. 



In Table III are recorded the results of a direct comparison of the 

 behaviour of the seeds towards dextrose and cane sugar in comparison with 

 sodium chloride, in weight normal solutions. It will be seen that, although 

 distinctly less active than salt, these two substances both inhibit the 

 absorption of water to a very marked extent, being about equally effective. 



Table III. 



Solute. 





Percentag 



e of water absorbed in — 





2 days. 



4 days. 



6 days. 



7 days. 



11 days. 





29 -5 



34 -3 



36 -2 



36 -9 



38 -4 





30 -2 



35 "8 



38 -1 



38 -3 



39 -8 



NaCl 



28 -1 



31 -9 



34 -2 



34 -4 



35 -5 



Selective Permeability of the Seed-coverings of H. vulgare. 



Mercuric Salts. — When barley seeds are steeped in a 3-per-cent. solution 

 of mercuric chloride in water, the salt may be detected within the seed 

 covering after a few hours ; after two or three days it is usually found 

 diffused throughout the whole of the interior portions of the seeds. 



At first it seemed possible that the passage of the salt into the seed 

 ought not to be regarded as proof of a selective property of the seed- 

 covering, but perhaps merely as an indication that the action of the salt 

 destroyed their semi-permeable character. Experiment, however, has proved 

 conclusively that this is not the case. When seeds which have been steeped 



