58 ENZYMES OR SOLUBLE FERMENTS. 



ther action of the enzyme on tlie first-formed maltose. 1 But this 

 is by no means quite certainly the case, and without doubt no 

 dextrose is obtained during a digestion of moderate duration. 

 The pancreatic enzyme, on the other hand, not only rapidly con- 

 verts starch into maltose, but further converts this maltose into 

 dextrose in considerable quantity during a digestion of relatively 

 short duration in comparison with that required for its production 

 by the action of ptyalin. 2 The secretion of the pancreas is of ex- 

 tremely complicated composition, and contains in addition to the 

 amylolytic at least two other well characterised enzymes ; from 

 these the former has as yet been only very imperfectly separated, 

 so that scarcely anything is known of its chemical nature as dis- 

 tinct from its converting powers. According to von Wittich the 

 amylolytic enzyme is separable from the others by treating the 

 gland with ether and alcohol before its extraction with glycerine, 

 to which reagent it then yields only the amylolytic enzyme ; 8 

 Hiifner, however, obtained a mixture of enzymes by von Wittich's 

 method. 4 Experiments on the separation of the enzymes have 

 also been made by Danilewsky 5 and Paschutin ; 6 but the most 

 successful outcome of any method which may be employed simply 

 results in the production of an extract which is preponderatingly 

 amylolytic, but is by no means free from the other enzymes. An 

 active amylolytic .extract is best prepared by Roberts' method, 7 in 

 which the finely minced pancreas is extracted for five or six days 

 with four times its weight of 25 p.c. alcohol, the mixture being 

 frequently stirred. The pancreas of the pig yields the most cer- 

 tainly active extracts, and more particularly if the gland is kept 

 for 24 hours after removal from the body, and is then treated for 

 a few hours with dilute (-5 p.c.) acetic acid before its final ex- 

 traction with alcohol. 



Benger's ' liquor pancreaticus ' is, when freshly prepared, possessed 

 of extraordinarily active araylolytic powers. From it an extremely 

 pure and active solution of the enzyme may be obtained by adding to 

 it four times its volume of strong alcohol and filtering off the precipi- 

 tate thus formed; the precipitate is then rapidly washed with alcohol, 

 dried in the air, and dissolved in water. 



The secretion and extracts of the small intestine possess to a 



1 Musculus mid Gruber, Zt.f. pht/siol. Chem. Bd. n. (1878), S. 177. Musculus 

 uud T. Mering, Ibid. S. 403. v. Mering, Ibid. Bd. v. (1881), S. 185. 



2 Brown and Heron, Liebig's Ann. Bd. cxcix. (1879), S. 165. Ibid. Bd. cciv, 

 (1880), S. 228. Proe. Roy. Soc. No. 204 (1880), p. 393. Confirmed also by the 

 author's own experiments. 



3 Pfliiger's Arch. Bd. 11. (1869), S 198. 



* Hiifner, Jn.f.prakt. Chem. N. F. Bd. r. (1872), S. 372. 



5 Virchow's Arch. Bd. xxv. (1862), S. 279. But see Lossuitzer, Dtss. Leipzig, 

 1864. 



B Arch. f. Anat. u. Physiol. Jahrg. 1873, S. 382. 



Proc.'Roy. Soc. Vol. xxxn. (1881), p. 145. See also Digestion and Diet, 1891, 

 pp. 16, 69. 



