224 WILLIAM EUGENE PICKLER 



(1911) and Shull (1913) have applied and extended this method. 



A definite quantity of barley grains was placed directly into 

 a saturated solution of LiOl. This, according to Shull (1913), 

 gives the highest osmotic pressure of any known neutral salt 

 and he found that the seeds of Xanthium were unable to take up 

 water from a saturated solution. This means that the osmotic 

 pressure of the salt — 965.3 atmospheres — is greater than the 

 force of imbibition of the seeds. In solutions of less density it 

 was possible for the seeds of Xanthium to take up water until 

 the imbibition force of the seeds and the osmotic power of the 

 solution were in equilibrium. Brown (1909) had found that the 

 coats of the barley grain are semipermeable and that seeds 

 extracted water from solutions of H 2 S0 4 , NaN0 2 , CuS0 4 , etc. 

 Tests showed that the coats of barley are impermeable to LiCl 

 in solution and solutions of this salt were chosen in preference to 

 the solutions used by Brown. Much to my surprise the barley 

 grain took up considerable water from a saturated solution of 

 LiCl thus showing it to possess an imbibition force much greater 

 than that of Xanthium. 



Twelve test tubes each with 10 cc. of a saturated solution of 

 LiCl were heated in a water bath to 30°C. Into each tube 100 

 air-dry barley grains, the weight of which had been previously 

 determined were placed. Each tube was stoppered with a per- 

 forated rubber stopper with a capillary tube to allow an equali- 

 zation of pressure during the heating. The tubes were then 

 immersed in the water bath, so that the upper end of the glass 

 tube only projected above the water. An equal number of sam- 

 ples of barley grains were treated in a like manner except that dis- 

 tilled water was substituted for the salt solution. Tubes con- 

 taining air-dry barley served as checks. At intervals of 2 hours, 

 three tubes, one containing a sample in the salt solution, the 

 second containing a sample in distilled water, and the third, 

 containing the air-dry check, were removed from the bath. 

 The grains were superficially dried and their weight again 

 determined. They were then placed on wire nets and dried in 

 a current of warm air. 



