34o CHEMISTR Y OF THE DIGESTIVE PROCESSES. 
is probable that it is capable of splitting up all the fat of a full meal 
iu the ordinary time of digestion within the body. 1 
Pialyn acts on other esters than the neutral fats causing a similar 
saponification. 2 
Separation of the pancreatic enzymes.— There has, strictly speak- 
ing, been no complete isolation of the pancreatic enzymes obtained by 
the various workers on the subject. Partial success has been so far 
obtained, in that methods have been invented which yield solutions 
much richer in one of the two principal enzymes than in the other. 
Danilewski 3 was the first to tackle this difficult task, under the direction 
of Kiihne. He found that, after shaking up a watery infusion of the 
pancreas of the dog with excess of magnesia, and filtering, there remained an 
infusion which possessed only a proteolytic and diastatic action. 
This solution was mixed up with one quarter of its volume of thick collodion 
solution (in alcohol and ether), and thoroughly shaken. The collodion is 
thrown out of solution as a pasty mass, which mechanically carries with it 
the proteolytic ferment, while the diastatic ferment remains in solution. 
The collodion is removed, washed, and dissolved in a mixture of alcohol and 
ether. This solution is allowed to stand for some days, when the proteolytic 
ferment with a little proteid falls to the bottom as a yellow sediment. This 
sediment, when dissolved again in water, digests fibrin in alkaline or neutral, 
not in acid solution. The filtrate from the collodion, which contains the 
diastatic enzyme, is evaporated down in vacuo, and filtered from anything 
which precipitates out. The filtrate is precipitated by excess of absolute 
alcohol, extracted by a mixture of 2 parts water to 1 part alcohol, and 
dried in vacuo. The solution so obtained rapidly converted starch into 
sugar, and only possessed a very feeble action on fibrin. Lossnitzer 4 has 
repeated these experiments, and only partially confirms them. Neither of 
the two products obtained by Danilewski gave the xanthoproteic, or Millon's 
reactions. 
Cohnheim 5 obtained the diastatic enzyme from an infusion of pancreas, by 
a method identical with that by which he obtained ptyalin. 6 This substance 
possessed no proteolytic action, did not give the proteid reactions, but acted 
very energetically on starch. 
v. Wittich 7 made use of the insolubility of trypsin in dry glycerin to 
obtain an extract rich in diastatic ferment and free from proteolytic action. 
The pancreas is dehydrated in strong alcohol, and further allowed to stand 
under absolute alcohol for some time ; the tissue is then dried and extracted 
with dry glycerin ; the extract after filtration is precipitated by excess of 
alcohol, and the precipitate is again extracted with dry glycerin. In this 
manner v. Wittich obtained an extract which did not act on fibrin and had 
an intense action on starch. Hiifner got an extract, on repeating the process, 
which also contained trypsin ; but as Kiihne states that trypsin is not soluble 
in gl} T cerin, Hiifner's results may be due to water in the glycerin em- 
ployed. 
Paschutin 8 attempted to separate the pancreatic enzymes by using as 
1 All these observations on the rapidity of action of this enzyme, and its variations, 
have been made by Rachford, Journ. Physiol., Cambridge and London, 1891, vol. xii. 
p. 72. 
2 Berthelot. Ann. d. chim., Paris, 1854, tome xli. p. 272 ; Nencki, Arch. f. exper. Path. 
u. PharmakoL, Leipzig, 18S6, Bd. xx. S. 367 ; Baas, Ztschr. f. physiol. Chan., Strassburg, 
1890, Bd. xiv. S. 416. 
3 Virchow's Archiv, 1862, Bd. xxv. S. 279. 
4 Arch. d. Hcilk., Leipzig, 1864, Bd. v. S. 556. 
5 J'irchow's Archiv, 1863, Bd. xxviii. S. 241. B See p. 328. 
1 Arclt.f. <!. ges. Physiol., Bonn, 1869, Bd. ii. S. 198. 
8 Arch. f. Anut. %, Physiol., Leipzig, 1873, S. 382. 
