/ '. iRL I TIONS IN PANCREATIC JUICE. 
553 
the zymogen is not soluble in water, thus contrasting markedly with 
other zymogens. We must regard the existence of a precursor in 
this case as doubtful, though it is undeniably possible that in the 
living cell an ante- 
cedent state of the 
ferment exists, adapted 
to storage of the fer- 
ment ; in that case the 
mere destruction of the 
cell might involve the 
breaking down of this 
I iv] lothetical zymogen, 
on account of the pre- 
cursor of the diastatic 
ferment being less 
Btable than that of the 
proteolytic. 
There is also no 
evidence of any zymo- 
gen of the fat-decom- 
posing ferment, pialyn. 
Finally, it has been 
4 
■3 
1 
€ 7 6 9 to II IZ 13 1+ 15 16 17 IS i<i 
Fig. 46. — Chart of the course of secretion of pancreatic juice. 
The abscissa; correspond to hours ; the ordinates corre- 
spond to c.c. of juice. — After Heidenhaiu. 
found that extracts of pancreas and the pancreatic juice itself 1 have 
the power of inducing a clot in milk, probably by the agency of some 
specific enzyme in the juice. 
The variations in the composition and amount of pancreatic 
juice during digestion. — From the earlier experiments of Bern- 
stein,' 2 and those of 
Heidenhain, 3 it ap- 
pears that the flow 
of pancreatic juice 
has somewhat the 
following course: — 
Before a meal 
is over there com- 
mences a secretion, 
whi ch reaches a 
maximum not later 
than the third hour. 
Then the secretion 
sinks to about the 
sixth or seventh 
hour, and yet again 
increases to the 
ninth or eleventh : 
thence it sinks gra- 
duallv to about the 
75 
TO 
6-5 
C.O 
5-5 
SO 
16 
40 
3-5 
■3.0 
2-5 
2<0 
1-5 
1-0 
•5 
i 2 a ? 5 e 7 e 9 io u ir. i<3 m 15 >e n ism 
Fig. 47. — Chart of the percentage composition of the flow of 
pancreatic juice. The abscissae correspond to hours ; the 
ordinates to percentage of solids. — After Heidenhain. 
eighteenth and twentieth. The quality of the juice varies inversely as 
the quantity. When one rises the other falls. The accompanying 
diagrams (Figs. 46 and 47) illustrate these variations. 
1 Halliburton and Brodie, Journ. Physiol., Cambridge and London, 1S96, vol. xx. 
2 Op. cit. 
'■' Hermann's " Handbuch," lid. v. 
