178 THE PROCESSES OF DIGESTION AND RESORPTION. 



troduced the generic term proteose8, and according to their individual 

 origin divides the proteoses into globulinoses, vitelloses, fibrinoses, 

 myosinoses, seroses, etc. Their stages of digestion are further indi- 

 cated by the prefixes proto-, hetero-, and deutero, so that we speak 

 of a proto- and a hetero-vitellose, of deutcro-caseoses, etc. 



Digestion of the Proteids. 



The digestion of the proteids, or of the nucleo-albumins, the 

 glucoproteids, and the haemoglobins at least, like that of the native 

 albumins, begins in the stomach. Here the separation of the non- 

 albuminous pairling is first effected, and is then followed by the 

 digestion of the liberated albumins. This digestion is in all respects 

 analogous to that of the native albumins proper. Syntonins are first 

 formed, then primary albumoses, subsequently secondary albumoses, 

 and finally peptones i. e., bodies which still give the biuret reac- 

 tion, but which in contradistinction to the albumoses are not pre- 

 cipitated by salting with ammonium sulphate. The individual 

 products which thus result from the proteids have not as yet been 

 studied with the same care as those which are derived from the 

 native albumins, but it is likely that here also Kiihne's schema of 

 digestion does not apply in its original form. Individual differ- 

 ences also no doubt exist between the various digestive products 

 according to their origin, but of these also we know but little. 



Of special interest are the earlier phases of digestion of the 

 casein of milk. This normally exists in the milk in solution as a 

 neutral calcium salt. In the stomach a transformation into the 

 corresponding acid salt is then first effected by the hydrochloric 

 acid of the gastric juice, and followed by the action of the chymosin. 

 According to Hammarsteu, this effects a partial decomposition of the 

 soluble acid salt with the formation of calcium-paracasein, and a 

 small amount of an albumose-like posset albumin. The paracasein 

 is then precipitated and decomposed, with the formation of the cor- 

 responding paranuclein and the albuminous pairling. 



Of the fate of the non-albuminous components of the proteids 

 but little is known. The paranuclein of casein, it is stated, undergoes 

 solution on continued digestion in vitro, but is at the same time de- 

 composed with the formation of a small amount of orthophosphoric 

 acid and an organic acid, which likewise contains phosphorus. Of 

 this, however, nothing further is known (see also page 77). 



The nucleins proper are not digested in the stomach and remain 

 undissolved. 



Under the influence of the pancreatic juice casein is digested in 

 very much the same manner as with the gastric juice, but in this 

 case the transformation into paracasein is brought about through 

 the influence of the chymosin of the pancreas in an alkaline medium. 

 Caseoses then result as with the common native albumins, and finally 

 peptone is formed. 



