338 CHEMISTR Y OF THE DIGESTIVE PROCESSES. 
finds that hydrochloric acid alone does destroy trypsin, but not so 
rapidly as when pepsin is also present. 
All possible opinions have been held by various observers as to the 
reaction with which trypsin acts, and acts best ; 1 it is now generally 
accepted that it can act either in an alkaline, neutral, or very faintly 
acid solution, but that the optimum reaction is that given by about 1 
per cent, sodium carbonate (jSTa 2 Co 3 ). 2 
Active proteolysis by trypsin cannot take place in presence of an 
acid reaction, except the acid be combined with proteid. If the proteid 
be completely saturated with acid, the rate is greatly slackened even 
when there is no free acid in the solution ; and if much proteid be 
present, the ferment action may be abolished even before this stage is 
reached. 3 
Heidenhain 4 states that the concentration of sodium carbonate 
necessary to ensure maximum activity varies with the richness in 
ferment of the solution experimented upon ; the richer in ferment, the 
lower the percentage of sodium carbonate necessary for maximum 
action. 
Other alkaline carbonates are much less effective than sodium 
carbonate in increasing the activity of trypsin. The action is also said 
to be assisted, but to a still less degree, by other salts of the alkalies. 5 
Organic acids have not nearly so destructive an action as hydro- 
chloric acids, arsenious acid has no hindering effect, and salicylic acid 
only when in saturated solution. 6 
The nature of the proteid submitted to digestion by trypsin has 
also a profound effect upon the rapidity of the process. Fresh unboiled 
fibrin is so quickly dissolved that it cannot be used as a comparative 
test for trypsin, and fibrin which has been boiled, or discs of hard-boiled 
white of egg, must be substituted for it. 
Amylopsin.— An active amylolytic extract of pancreas can best be 
prepared by following Koberts' method of extracting with dilute alcohol. 
Pancreatic juice is much more intensely diastatic than saliva, but 
it cannot be determined, until some method for isolating the diastases 
has been discovered, whether this is due to a difference in the amylolytic 
ferments present or to a mere difference in concentration. It is certain, 
however, that salivary, pancreatic, and malt diastases are practically 
identical in the qualitative character of their action on starch. Eoberts 
1 See Corvisart, "Collection de memoires sur une function peu connue du pancreas, la 
digestion des aliments azotes," Paris, 1857-8, p. 41 ; Meissner, Ztschr. f. rat. Med., 1859, 
3 Reihe, Bd. vii. S. 17 ; Kiihne, Verhandl. d. naturh.-med. Ver. zu Heidelberg, N. F., 
Bd. i. S. 190 ; Danilewski, Virchow's Archiv, 1862, Bd. xxv. S. 291 ; May, Untcrsuch. a. d. 
physiol. Inst. d. Univ. Heidelberg, 1880, Bd. iii. S. 378 ; Lindberger, Jahresb. ii. d. Fortschr. 
d. Thier-Chem., Wiesbaden, 1883, Bd. xiii. S. 280; Ewald, Ztschr. f. Uin. Med., Berlin, 
1880, Bd. i. S. 615 ; Langley, Joum. Physiol., Cambridge and London, 1880-2, vol. iii. 
p. 262. 
2 Weiss, Virchow's Archiv, 1876, Bd. lxviii. S. 413 ; Melzer, Inaug. Diss., Erlangen, 
1894. According to the latter author, a digestion which is complete in two and a half 
hours with 1 per cent. Na.,C0 3 is incomplete in twenty-four hours with either 3 per cent. 
Na 2 Co 3 or 0-010 per centfof HC1. 
3 Chittenden and Cummins, Stud. Lab. Physiol. Chem., New Haven, 1885, vol. i. p. 100. 
4 Hermann's "Handbuch," Bd. v. (1), S. 187. 
5 Podolinski, " Beitr. z. Kenntniss des pankreatische Eiweissfermentes," Breslau, 1876, 
S. 43. See also Chittenden and Cummins, loc. cit., who found that borax and potassium 
cyanide augment, while salts of mercury and iron decrease, the activity. 
"Lindberger, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 18S3, Bd. xiii. 
S. 280: Schaferu. Bohm, ibid., 1872, Bd. ii. S. 363; Kiihne, Verhandl. d. naturh.-med. 
Ver. mi Heidelberg, N. F., Bd. i. S. 190. 
