50 THE: PROTEINS OF THE WHEAT KERNEL. 



became perfectly clear, but later deposited a large coherent precipitate, which, 

 gradually contracted, but at the same time retained the form of the lower 

 part of the beaker. From this the clear solution was decanted, the precip- 

 itate thoroughly washed by decantation, suspended in water and dissolved 

 by adding 28 cc. of decinormal potassium-hydroxide solution, an amount of 

 alkali just sufficient to dissolve all the substance, and at the same time make 

 the solution neutral to litmus. When to this solution decinormal acid was 

 gradually added, no precipitate appeared until nearly one-half the quantity 

 of acid required for complete neutralization had been added, but with 28 cc. 

 the solution was neutralized and the nuclein completely precipitated, the 

 addition of 2 cc. more acid giving no turbidity in the filtered solution. This 

 precipitate formed preparation 52, weighing 1.54 grams. 



To precipitate this substance a quantity of acid was added exceeding that 

 of the alkali employed for solution by just 2 cc. The filtrate from the pre- 

 cipitate, however, required not 2 cc. of alkali, but 8.5 cc. for neutralization 

 to phenolphthalein, showing 6.5 cc. of alkali to have been neutralized by 

 the acid of the nuclein originally dissolved. The neutralized filtrate left on 

 evaporation 0.3975 gram of substance, the aqueous solution of which was 

 precipitated by hydrochloric or nitric acid, but not by ammonium molybdate 

 solution until after boiling with acid for some little time, when yellow phos- 

 phomolybdate was precipitated. These facts indicate the presence in this 

 filtrate of a nucleic acid. 



More nuclein was made from the same preparation, 7, by suspending 30 

 grams in 0.2 per cent hydrochloric acid containing pepsin, which, even at 

 20, caused within 2 hours complete solution of the coagulated protein. 

 The solution was digested at 37 for 48 hours, during which time much 

 nuclein separated, having the appearance and properties of the preparation 

 just described. 



After decanting the clear solution and thoroughly washing the residual 

 nuclein, the latter was suspended in water and dissolved in 72 cc. decinor- 

 mal potassium-hydroxide solution. The solution thus obtained was made 

 neutral to litmus by adding u cc. of decinormal hydrochloric acid, but no 

 precipitate appeared till 1.5 cc more of acid were added. To the solution 

 72 cc. decinormal hydrochloric acid were added, giving a precipitate, prepa- 

 ration 53, which weighed 3.4 grams. The filtrate from this precipitate, as 

 in the former case, was strongly acid, requiring 12 cc. of decinormal potas- 

 sium hydroxide to neutralize it to phenolphthalein. Two other preparations 

 of nuclein were made from 8.493 grams of 13 and 9.804 grams of 16, both 

 being substances precipitated from the aqueous extract by saturating with 

 sodium chloride. Each portion was suspended in about 300 cc. of 0.2 per 

 cent hydrochloric acid, containing o. i gram of pepsin, and, with frequent 



