5 5 2 ME CHANISM OF SEC RE TION OF PANCREA TIC JUICE. 
Heideubain established definite characters distinguishing tripsinogen 
from the actual enzyme, and showed that in some respects their behaviour 
was similar. The chief relations of the zymogen to the ferment are as 
follows : — 
1. Trypsinogen is soluble in glycerin. Some glycerin extracts of 
pancreas have no ferment activity, since the ferment is in the condition 
of zymogen, but if such glycerin extracts, dissolved in 1 per cent, 
sodium hydrate, be diluted with distilled but not boiled water (this 
being largely devoid of dissolved air), especially if digested for a time 
at 40° C, it will become active. 
2. If an inactive glycerin extract of fresh pancreas be dissolved in 
sodium carbonate, 1 to 2 per cent., the passing through it of oxygen 
will cause the same to become active. 
3. Platinum black will, according to Podolinski, 1 also render the 
inert extract proteolytic, 
4. The converse of the change brought about by the influence of 
oxygen may also occur, for, through the deprivation of oxygen, activity 
becomes lost. 
5. If fresh pancreas be mixed with the same weight of 1 per cent. 
acetic acid for ten minutes, and then placed in glycerin, a very active 
extract will lie obtained. The acetic acid converts the trypsinogen into 
trypsin. According to Kuhne, 2 trypsin is also formed from the zymogen 
by warming with alcohol. 
The amount of trypsin that can be obtained from an extract varies 
with the histological condition of the gland. When the luminal zone 
is of considerable width, a greater amount of proteolytic activity is 
shown than when it is much reduced. We are justified in associating 
the ferment with the granules seen in the cells. 
Sodium carbonate may be regarded as an adjuvant to the action of 
trypsin. Kuhne 3 showed that it worked best in solutions of the strength 
of 1 per cent. Edkins 4 proved that sodium chloride has a beneficial 
influence on the digestion of fibrin by pancreatic extracts, and it may be 
noted that a large amount of the sodium carbonate associated with the 
pancreatic secretion must be converted into sodium chloride in the 
duodenum. Ewald 5 states that digestion of fibrin at the instance of 
trypsin can proceed in the presence of 0*3 per cent, of hydrochloric acid, 
but, on the other hand, the prolonged action of dilute acids has been 
shown by Langley 6 to be destructive of trypsin. If a glycerin extract 
of pancreas lie warmed fur two and a half hours in O'Oo per cent, hydro- 
chloric acid, its proteolytic powers are appreciably curtailed. The 
diastatic ferment has not had the same study bestowed upon it as the 
proteolytic. It contrasts with this latter in that there is no further 
enhancement of its activity by treatment with such reagents as convert 
trypsinogen into trypsin. Liversedge 7 made observations in 1874, 
which suggested the existence of a diastatic zymogen, but the possi- 
bility of micro-organic change influencing his experiments was, as 
pointed out by Gamgee, 8 not eliminated. According to his observations, 
1 Breslau, 1876. 
- Verhandl. d. natiwh.-med. Ver. ~u Heidelberg, 1876, N. F., Bd. i. 
3 Ibid., Bd. i. 4 Jouru. Physiol., Cambridge and London, 1891 Bd. xii. 
5 Ztschr.f. klin. Med., Berlin, Bd. i. 
G Joum. Physiol., Cambridge and London, vol. iii. 
7 Journ. of Anat. and Physiol., London, 1874, vol. viii. 
8 " Physiological Chemistry," vol. ii. p. 207. 
