THE END-PRODUCTS OF ALBUMINOUS DIGESTION. 201 



neutral solution. It consists of two fractions, which can be differ- 

 entiated from each other and the gluco-albumose by means of alco- 

 hol. 35 per cent, alcohol will precipitate the deutero-albumose B ; 

 the gluco-albumose is then thrown down in the presence of 60 to 70 

 per cent. ; while the B fraction remains soluble even with 80 per 

 cent. Deutero-albumose B, in the case of fibrin at least, is formed 

 only in traces, and may indeed be absent. It does not give the re- 

 action of Molisch ; the biuret reaction is intense and the sulphur 

 reaction marked. It contains 16.94 per cent, of nitrogen. 



Deutero-albumose B. This usually represents the greater por- 

 tion of the secondary albumoses. It is not absolutely insoluble in 

 alcohol, but a large excess of strong alcohol is necessary to precipi- 

 tate it from a concentrated solution. The substance does not give 

 Molisch's reaction, nor does it contain loosely combined sulphur ; 

 the biuret, xanthoproteic, and Millon's reactions, however, are pres- 

 ent and the indol reaction is very pronounced. Elementary analysis 

 of this portion has not given constant results, which suggests that 

 the substance as obtained by Pick was not pure. He found as a 

 matter of fact that his material, which was obtained from Witte 

 peptone, was contaminated by a melanin-like body, which he termed 

 peptomelanin. The analytical figures follow: = 43.99-52.32, 

 H = 6.91-7.32, N = 14.25-15.38, S = 1.63-1.21, O = 33.23-23.79. 



Deutero -fraction C. This is precipitated on complete saturation 

 with ammonium sulphate, and carefully acidifying with sulphuric 

 acid saturated with ammonium sulphate. It is soluble in 76-80 per 

 cent, alcohol. In the case of fibrin deutero-albumose C is formed 

 only in small amount. It contains no loosely combined sulphur 

 and does not give the reaction of Molisch nor that of Millon, or to 

 so slight a degree only as to suggest contamination with other frac- 

 tions. On fusion with caustic alkali it yields neither indol nor 

 skatol. Elementary analysis has given the following results : 

 C == 34.52, H = 5.35, N = 17.24. 



The fraction apparently represents an end-product of peptic di- 

 gestion ; it yields no peptone (Pick). It is not formed during 

 tryptic digestion. The specific reactions of the individual fractions 

 are given in the accompanying tables (pages 202 and 203). 



THE END-PRODUCTS OF ALBUMINOUS DIGESTION. 



To study the end-products of albuminous digestion it is well to 

 digest fibrin for several weeks with trypsin as just described. Any 

 deutero-albumoses still remaining are removed and the antipeptone 

 fraction isolated as follows : 



Antipeptone Fraction. The mixture is filtered, slightly acidified 

 with acetic acid, boiled, again filtered, and concentrated to about 

 1000 c.c. On cooling, a good deal of ty rosin separates out and is 

 filtered off. The filtrate is diluted with water to about 2000 c.c., 

 neutralized, heated to near the boiling-point, and saturated with 



