144 RELATIONS OF PEPTONES TO PROTEIDS. [BOOK II. 



The Relations of Peptones to the Proteids from which they are 



derived. 



The facts, firstly, that peptones have approximately the same 

 composition as the proteids which give rise to them ; secondly, that 

 peptones are reconverted in the organism with the greatest readi- 

 ness into other albuminous bodies, render it well-nigh certain that 

 the change which the proteid molecule undergoes in passing from 

 the condition of a native albumin to that of a peptone is but a very 

 slight one. It has been surmised (Hoppe-Seyler 1 ) that peptones 

 are hydration products of their respective proteids, which are their 

 anhydrides. This view is borne out by the fact that peptones 

 may be produced not only by the action of the enzymes of the 

 alimentary canal (which by analogy with the action of ptyalin and 

 diastase on starch are undoubtedly hydrolytic), but by other hydro- 

 lytic agencies, as by the action of superheated water, or steam, and 

 by the prolonged action of dilute acids and alkalies, and of putrefac- 

 tion. In this case, as in many others, the hydration product is 

 characterized by a greater facility of entering into combination with 

 acids and bases. 



The view that peptones are products of hydration is supported by the 

 two following sets of experimental facts. 



1. Henninger heated 10 parts of fibrin-peptone with 25 parts of 

 acetic anhydride acid for an hour ; the acid was distilled off and the residue 

 was treated with hot water, which dissolved a great part. The watery 

 solution was dialysed, when there remained in the dialyser, a solution 

 which coagulated on boiling, on the addition of nitric acid, and when 

 treated with potassium ferrocyanide. 



2. Henninger and Hofmeister 2 have by merely heating peptone to 140 

 obtained a body which when dissolved in water possessed the characters 

 of a native albumin rather than of a peptone. 



Whether the change which an albuminous body undergoes in 

 being converted into a peptone is accompanied by hydration or not, 

 there can be little if any doubt that it is a change in which a com- 

 plex molecule is broken up into smaller molecules, and this surmise 

 is supported by the greater diffusibility of peptones as compared with 

 proteids. 



THE ACTION OF THE GASTRIC JUICE UPON THE SO-CALLED 

 " ALBUMINOID " BODIES. 



There is a group of bodies, which have been described in con- 

 nexion with the chemistry of the tissues of the animal body, which 



1 Physiologische Chemie, p. 227. 



2 Zeitschrift f. physiol. Chem., Bd. IT. (187879) S. 206. See also Pekelharing, 

 Pfliiger's Arch., Bd. xxn. (1880), S. 185, and xxvi. (1881), S. 515 ; Griessmayer. See 

 Maly's Ber., xiv. (1884), S. 26. 



