182 PHYSIOLOGICAL CHEMISTRY. 



with proteids insoluble or difficultly-soluble combinations. The 

 alkaloid compounds may also decrease the pepsin digestion (CHIT- 

 TENDED and ALLEN). A very large number of observations have 

 been made in regard to the action of foreign substances on artificial 

 pepsin digestion, but as these observations have not given any 

 direct result in regard to the action of these same substances on 

 natural digestion, we will not here further discuss them. 



The Products of the Digestion of Proteids by Means of Pepsin 

 and Acid. In the digestion of nucleo-albumin an insoluble residue 

 of nuclein always remains. Fibrin also yields an insoluble residue, 

 which consists, at least in great part, of nuclein, derived from the 

 form-elements enclosed in the blood-clot. This residue which 

 remains in the digestion of certain albuminous bodies is called 

 dyspeptone by MEISSNER. If the solution is filtered after a com- 

 plete digestion and neutralized, it gives in different cases a more 

 or less abundant precipitate of acid albuminate, or a mixture of 

 albuminates called parapeptone by MEISSKER. After filtering this 

 precipitate and concentrating the filtrate again, some proteid often 

 separates. If this precipitate be filtered, the filtrate will now con- 

 tain albumoses and peptones in the ordinary sense, while the so- 

 called true peptone of KUHNE may sometimes be entirely absent, 

 and in general is obtained in quantity worth mentioning only 

 after a more continuous and intensive digestion. The relationship 

 between the albumoses and peptones in the ordinary sense changes 

 very much in different cases and in the digestion of various 

 albuminous bodies. For instance, a larger quantity of primary 

 albumoses is obtained from fibrin than from hard-boiled-egg albu- 

 min or from the proteids of meat. In the digestion of unboiled 

 fibrin an intermediate product may be obtained in the earlier stages 

 of the digestion a globulin which coagulates at -j- 55 C. (HASE- 

 BROEK). For information in regard to the different albumoses and 

 peptones which are formed in pepsin digestion, the reader is 

 referred to previous pages (25-28.). 



KUHNE claims that the albumoses and peptones are the final 

 products in the pepsin digestion. HOPPE-SEYLER claims, on the 

 contrary, that amido-acids, leucin and tyrosin, are also found. 

 HIRSCHLER has tried to confirm this view by his investigations. 

 The methods used by him do not seem to be quite trustworthy 



