PEPTONE. ^7 



ammonium sulphate as a reagent ; when added to satura- 

 tion this salt readily precipitates all proteids except peptone. 

 Pure peptone was never obtained previous to this, but 

 always more or less mixed with proteoses. 



The earliest of Kiihne's observations showed him that 

 there are two varieties of peptone, hemi-peptone, which by 

 the pancreatic juice is further split into leucine, tyrosine, 

 etc., and anti-peptone, which resists this action. The cor- 

 responding intermediate proteoses may be termed hemi- 

 albumose and anti-atbumose respectively. 



More recent observations have shown that albumoses 

 may be classified in another way, according to their re- 

 actions and solubilities, into : — 



i. Proto-albumose ; soluble in hot and cold water and 

 dilute saline solutions, but precipitated by saturation with 

 sodium chloride or magnesium sulphate. 



2. Hetero-albumose ; insoluble in water, and therefore 

 precipitable by dialysing out the salt from its solutions. 

 Otherwise it closely resembles proto-albumose. 



3. Deutero-albumose ; soluble in hot and cold water, 

 and not precipitated by saturation with sodium chloride or 

 magnesium sulphate, but it is by saturation with ammonium 

 sulphate. It is thus in its reactions nearest to the peptones. 



Peptone itself resembles these albumoses by giving the 

 biuret reaction (pink colour with copper sulphate and 

 caustic potash), but differs from them in not being pre- 

 cipitable by ammonium sulphate nor by nitric acid. 



Neumeister has succeeded in discovering the relation- 

 ship between these two classifications of the albumoses. 

 Albumin may be considered to be composed of hemi- 

 albumin and anti-albumin ; the hemi-albumin in the first 

 stage of hydration is split into proto-albumose and hetero- 

 albumose ; the anti-albumin yields hetero-albumose and 

 acid albumin. The next stage in hydration is deutero- 

 albumose, and the final step is the conversion of the 

 deutero-albumose into peptone of the hemi and anti 

 varieties. 



The albumoses (proto and hetero) formed directly 

 from the albumin may be called primary albumoses. 



