340 CHEMISTR Y OF THE DIGESTIVE PROCESSES. 



is probable that it is capable of splitting up all the fat of a full meal 

 in 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 (fUarter 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 vacua, 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 glycerin, 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. PharmaTcoL, Leipzig, 1886, Bd. xx. S. 367 ; Baas, Ztschr. f. physiol. Chcm., Strassburg, 

 1890, Bd. xiv. S. 416. 



3 Firchow's Archiv, 1862, Bd. xxv. S. 279. 



4 Arch. d. Hcillc., Leipzig, 1864, Bd. v. S. 556. 



5 Firchow's Archiv, 1863, Bd. xxviii. S. 241. 6 See p. 328. 



7 Arch.f. d. ges. Physiol., Bonn, 1869, Bd. ii. S. 198. 



8 Arch.f. Anat. u. Physiol., Leipzig, 1873, S. 382. 



