Chittenden and Hart — Elastin and the Elastose Bodies. 29 



Digestion of elastin by pepsin-hydrochloric acid. 



An artificial gastric juice, free from both albumose and peptone, 

 was prejDared as follows ; the cardiac portions from the mucous mem- 

 branes of ten pigs' stomachs (820 grams) were placed in three litres 

 of 0*4 per cent, hydrochloric acid and warmed at 40° C. for two 

 weeks. The clear fluid filtered from the small residue of nuclein, an- 

 tialbumid, etc, was then saturated with ammoniiim sulphate to pre- 

 cipitate the pepsin. This was filtered ofi", washed with saturated 

 ammonium sulphate solution to remove any adherent peptone, dis- 

 solved in two litres of 0*2 per cent, hydrochloric acid and dialyzed 

 until the sulphate was entirely removed. The resultant solution 

 was mixed with an equal volume of 0*4 per cent, hydrochloric acid, 

 making a pure and active pepsin-acid mixture. 



In the first digestion of elastin, 150 grams of powdered elastin A, 

 1500 c.c. of the pepsin-acid mixture, and an equal volume of 0-4 per 

 cent, hydrochloric acid, were warmed at 40° C. for 75 hours. At the 

 end of this time the elastin was almost entirely dissolved. The acid 

 fluid was filtered from the small residue remaining, and neutralized 

 with potassium hydroxide, without giving any neutralization precipi- 

 tate. The reactions of the fluid showed plainly the presence of elas- 

 toses similar to those formed by the action of acid. Saturation of 

 the fluid with ammonium sulphate gave a heavy gummy precipitate, 

 in the filtrate from which, nothing having the reactions of peptone 

 could be discovered. 



Protoelastose. 



The ammonium sulphate precipitate was dissolved in water and the 

 neutral fluid saturated with sodium chloride, by which a heavy gummy 

 precipitate was formed, having all of the reactions described as char- 

 acteristic of protoelastose. The product was purified by several re- 

 precipitations with salt, then dialyzed and the solution evaporated to 

 dryness on a water-bath, the residue powdered and dried at 110° C. 

 until of constant weight. 



The composition of the substance (protoelastose A 2) is shown in 

 the accompanying table. 



In reactions, the product agrees exactly with the protoelastose 

 already described, being precipitated by the concentrated miner'al 

 acids, by acetic acid and potassium ferrocyanide, by 30 per cent, 

 acetic acid and sodium chloride, by strong potassium and sodium 

 hydroxide as well as by sodium carbonate. Its a<pieous solution, 

 likewise, shows tlu; peculiar action towards heat, already described ; 



