THE /'.I. XCREA TIC ENZ YMES. 339 
states that pancreatic diastase is capable of converting 40,000 times 
its weighl of starch into maltose and dextrin; Kroger, that 1 grm. of 
pancreatic juice, containing 0021 grm. of dry solid, of which in turn 
only a small fraction could be amylopsin, digested in half an hour 4*67 
grins, of starch. 
Influence of temperature. — The rate of conversion increases with 
rising temperature from C < '. to 30° C; from 30 I '. to 45° C. the rate 
is at a maximum and practically constant. Above 45° C. the action 
becomes slower with rising temperature, and ceases between 60° C. and 
70' C, the ferment being here destroyed. 1 
Influence of reaction. — Pancreatic diastase closely resembles salivary 
diastase in its behaviour to change in reaction of the medium in which 
it is dissolved. It seems to act best when neutralised or in presence 
of in in ute traces of acid; but a limit of acidity is soon reached beyond 
which the rapidity of action rapidly diminishes, and the enzyme itself 
is quickly dest roved.' 2 The optimum activity, according to Melzer's 
measurements, coincides with the presence of - 01 per cent, of hydro- 
chloric acid. 
Pialyn. — Very little is known of the fat-splitting enzyme, pialyn, of 
the pancreatic juice. That the action is due to an enzyme is shown 
by the following experimental observations : — (a) The action is de- 
stroyed when the pancreatic juice or active pancreatic extracts are 
boiled; (/>) it takes place in presence of antiseptics, and hence cannot 
be clue to bacteria. 3 
The enzyme is much less stable than either of the other two 
associated with it in pancreatic juice. It is especially susceptible to 
the action of acids, being quickly destroyed by all except the higher 
fatty acids, so that great care to avoid acidity of solution must be 
exercised in the preparation of it from the pancreas. Paschutin 4 
recommends for its extraction a dilute solution of sodium carbonate 
and bicarbonate in water, and Griitzner 5 that it should be extracted 
from the perfectly fresh pancreas with a solution containing 90 c.c. of 
glycerin to 10 c.c. of 1 per cent, sodium carbonate, ten times the weight 
of gland to be extracted being taken of this fluid. However extracted, 
if must be taken from afresh gland and not from one which has stood over 
a day, a* in the case of the other two enzymes, for thereby an acid reaction 
would be developed, and as a consequence the fat-splitting enzyme would 
be destroyed. 
The rapidity of action of the enzyme is at first increased by rising 
temperature. It acts almost twice as fast at 38° C. as at 18° C, but it 
is destroyed by boiling ; the temperature of destruction is not accurately 
known. 
It acts more slowly in the presence of - 25 per cent, of sodium 
carbonate than in neutral solution. 
Its activity is greatly increased by the presence of bile, still more 
by a mixture of bile and hydrochloric acid ; this increase in activity is 
due to the bile salts or bile acids, which have a similar effect. The 
rapidity of action of the enzyme is usually much underrated, and it 
1 Roberts, " Digestion and Diet," London, 1891, p. 71 ; Proc. Roy.- Soc. London, 1881, 
vol. xxxii. p. 145. 
2 Melzer, Inaug. Diss., Erlangen, 1894. 
■ J Xencki, Arch. f. exper. Path. a. Pharmakol., Leipzig, 1886, Bd. xx. S. 367. 
4 Arch. f. Anat.n. Physiol., Leipzig, 1873, S. 386. 
5 Arch. f. d. ges. Physiol., Bonn, 1876, Bd. xii. S. 302. 
