448 DIGESTION. 



found that the anions had a much greater retarding action upon pepsin 

 digestion than the cations. Of these latter the sodium cation had the 

 strongest retarding action. Alcohol in large quantities (10 per cent 

 and above) disturbs the digestion, while small quantities act indifferently. 

 Metallic salts in very small quantities may indeed sometimes accelerate 

 digestion, but otherwise they tend to retard it. The action of metallic 

 salts in different cases can be explained in various ways, but they often 

 seem to form with proteins insoluble or difficultly soluble combinations. 

 The alkaloids may also retard the pepsin digestion (CHITTENDEN and 

 ALLEN x ) . 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, as well as upon secretion 

 and absorption, we will not discuss them here. 



The Products of the Digestion of Proteins by Means of Pepsin and Acid. 

 In the digestion of nucleoproteins or nucleoalbumins an insoluble residue 

 of nuclein or pseudonuclein always remains, although under certain 

 circumstances a complete solution may occur. Fibrin also yields an 

 insoluble residue, which consists, at least in great part, of nuclein, derived 

 from the form-elements inclosed in the blood-clot. This residue which 

 remains after the digestion of certain proteins was called dyspeptone by 

 MEISSNER. This name is therefore not only unnecessary but indeed 

 erroneous, as this residue does not consist of bodies related to the pep- 

 tones. In the digestion of proteins, substances similar to acid albumi- 

 nates, parapeptone (MEISSNER 2 ), antialbumate, and antialbumid (KUHNE), 

 may also be formed. On separating these bodies the filtered liquid, 

 neutralized at boiling-point, contains proteoses and peptones in the old 

 sense, while the so-called KUHNE true peptone and the other cleavage 

 products are obtained only after a longer and more intense digestion. 

 The relation, between the proteoses, changes very much in different 

 cases and in the digestion of the proteins. For instance, a larger 

 quantity of primary proteoses is obtained from fibrin than from 

 hard-boiled egg-albumin or from the proteins of meat; and the dif- 

 ferent proteins, according to the researches of KLUG, S yield on pepsin 

 digestion unequal quantities of the various digestive products. In the 

 digestion of unboiled fibrin an intermediate product may be obtained 

 in the earlier stages of the digestion a globulin which coagulates at 



1 Studies from the Lab. Physiol. Chem. Yale University, 1, 76. See also Chitten- 

 den and Stewart, ibid., 3, 60. 



2 The works of Meissner on pepsin digestion are found in Zeitschr. f. rat. Med., 7, 

 8, 10, 12, and 14. 



3 Pfliiger's Arch., 65. 



