VEGETABLE PROTEINS 47 



This extract is then saturated with pure ammonium sulphate. 

 The copious precipitate is collected on a filter and, after the com- 

 pletion of filtration, dissolved in about 800 cc. of water. The 

 solution is then filtered and placed in a dialyser. After twenty- 

 four hours a considerable precipitate has formed, which is seen 

 under the microscope to consist entirely of perfectly formed 

 octahedral crystals. After dialysing for about five days the solu- 

 tion is found to be free from chlorides, and the precipitate is then 

 filtered off and washed with water, followed by dilute alcohol 

 gradually increased in strength to absolute alcohol; it is finally 

 washed with ether and dried over sulphuric acid. 



The preparation, after drying, still retains its crystalline char- 

 acter. The meal yields about 10 per cent of its weight in globulin. 



(6) Extraction with sodium chloride solution. 



One hundred grams of the flax-seed meal are extracted three 

 successive times with 20 per cent sodium chloride solution, and 

 the clear, filtered, bright yellow extracts are united and dissolved 

 in 10 per cent sodium chloride, and this solution, after filtering 

 off an insoluble residue, is submitted to dialysis. After five days 

 the solution, free from chlorides, is filtered and the precipitate 

 washed with water, alcohol and ether and dried. The prepara- 

 tion, after drying, still retains its crystalline character. One 

 hundred grams of meal yield about 11.6 grams of protein. This 

 protein is identical with the globulin obtained by extraction with 

 water. 



(c) Extraction with dilute KOH solution. 



Flax-seed globulin, prepared by either of the above methods, is 

 soluble in dilute KOH and can be precipitated from this solution 

 unchanged in composition or properties, by cautious neutraliza- 

 tion with hydrochloric acid. 



Flax-seed meal is extracted with 100 cc. of 0.01 KOH per 

 gram. After filtration it is saturated with ammonium sulphate 

 and the precipitate filtered off and dissolved as completely as 

 possible in 10 per cent sodium chloride. This solution is dialysed 

 until the chlorides are removed and the subsequent treatment is 

 the same as that employed in the two previous preparations. 



This preparation is imperfectly crystalline, but identical in 

 composition with the other preparations. One hundred grams 

 of meal yield about 17.5 grams of protein. 



The plant globulins are, like serum globulin, precipitable from 



