DIGESTION 31 



the peptone stage. Indeed, in general the process goes 

 only as far as the proteose stage as may be seen from 

 the following table from London. In these experi- 

 ments dogs were fed different types of proteins and 

 from a fistula below the pylorus the products were 

 collected. 



Kind of Protein Fed Percentage of Proteases Found 



Egg Albumin 72.5 



Gliadin 67.7 



Edestin 60.3 



Casein 59.1 



Gelatin 50.6 



Serum Albumin 46.1 



London and his co-workers also found that upon 

 feeding varying quantities of the same protein a defi- 

 nite proportion of proteoses was always formed, thus 



Quantity of Gliadin Fed Percentage of Proteoses Found 

 in grams 



25 80.8 



50 86.1 



75 86.5 



100 84.9 



It is therefore probable that ingested protein enters 

 the duodenum largely in the form of proteoses and to 

 a smaller extent as peptones. 



By long continued action of both artificial and nor- 

 mal gastric juice various investigators have observed 

 the gradual formation of amino acids. These results 

 obtained from digestive mixtures allowed to stand for 

 months cannot be regarded as applicable to normal 



