100 THK ROLE OF NITROGEN IN PLANT-METABOLISM, iii., 



containing protein in suspension, much of the latter may be 

 redissolved, and still any increase in the concentration of 

 hydroxyl ions is avoided. This in no way resembles the con- 

 ditions of extraction by dilute alkalies. 



The following comparative tests were made on the solu- 

 bility of the seed-proteins in various concentrations of sodium 

 chloride, sodium hydroxide, and the two together. 



Method. — Two grammes of finely-powdered seeds were ex- 

 tracted, for 24 hours, with the solvents stated in Table ii., 

 and frequently shaken. All the extracts reacted acid to 

 phenolphthalein, but alkaline to litmus. An equal volume of 

 each clear filtered extract was then transferred to a centrifuge 

 tube, and precipitated by the addition of 6 drops of salicyl- 

 sulphonic acid. After spinning, the supernatant fluids were 

 decanted, and the deposits were washed free from acid 

 (neutral to phenolphthalein). 



To each tube was then added 20 cc. of 1% saline solution, 

 and the opalescent fluids titrated with sodium hydroxide. 

 After titration, each was transferred to a Kjeldahl flask, and 

 this nitrogen determined. The results are given in the table 

 below : — 



Tablk ii. 



