EXPERIMENTAL. cj! 



stirring, digested at 40 for 24 hours. Throughout the digestion a large 

 part of the substance remained undissolved. An equal volume of 0.2 per 

 cent hydrochloric acid, containing o. i gram of pepsin, was again added to 

 each, and the digestion continued for 24 hours longer. The insoluble matter 

 which remained was not coherent like the two former nuclein products, but 

 consisted of a white, very finely divided substance, which was easily filtered 

 out and washed. From 13, 4.04 grams of preparation 54 were obtained, 

 and from 16, 4.16 grams of 55. 



GLOBUWN NUCLEATE. 



Fifteen grams of a mixture of nearly equal parts of the globulin prepa- 

 rations 32 and 33 were next suspended in 0.2 per cent hydrochloric acid 

 containing 0.2 gram of pepsin, which, within a short time, almost completely 

 dissolved the protein matter. From this solution, on further digestion, the 

 nuclein separated, forming a coherent deposit. After 72 hours' digestion 

 the clear solution was decanted, the deposit dissolved in a little ammonia, and 

 its solution filtered perfectly clear from a very slight gelatinous residue. 

 The solution was then treated with acetic acid added in excess of the 

 amount necessary to neutralize it to litmus. Since, even on standing, the 

 precipitate so produced separated imperfectly, an equal volume of alcohol 

 was added. The substance, which then separated well, gave 2.38 grams of 

 preparation 56, or about 16 per cent of the original substance. 



The filtrate from the acetic acid precipitate, on adding hydrochloric acid, 

 gave a further slight precipitate, which had properties characteristic of 

 nucleic acid. 



Still another preparation of nuclein was made from the globulin by sus- 

 pending 10 grams of 36 in water and adding 50 cc. of decinormal potassium- 

 hydroxide solution. This solution was neutralized and an equal volume of 

 0.4 per cent hydrochloric acid at once added, producing a turbid solution, 

 which, however, contained no visible particles. To this pepsin was added 

 and the mixture digested for 40 hours, during which time a coherent deposit 

 of nuclein formed on the bottom of the beaker. From this the clear solution 

 was decanted. The deposit was then thoroughly washed with water and 

 dissolved in 43 cc. of decinormal potassium-hydroxide solution. To this 

 clear solution 43 cc. of decinormal hydrochloric acid were added, causing a 

 gummy precipitate, which could not be filtered until 15 cc. more acid had 

 been added, when the precipitate rapidly settled as a coherent deposit, from 

 which the solution was soon decanted. This solution required for neutrali- 

 zation to litmus 1 6 cc. of decinormal potassium-hydroxide solution, and to 

 phenolphthalein 18 cc. The precipitate when washed and dried gave 2.2 

 grams of preparation 57. 



