58 ENZYMES OR SOLUBLE FERMENTS. 



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 

 certainly 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 extraction with 

 alcohol. 



Benger's ' liquor pancreaticus ' is, when freshly prepared, possessed of extra- 

 ordinarily active amylolytic 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 precipitate 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 

 slight extent the power of slowly hydrolysing starch into maltose ; the 

 conversion being more rapid if portions of the mucous membrane of 

 the intestine be finely divided and immersed in the starch solution 1 . 

 The tissue and its extracts on the other hand possess to a very 

 marked extent the power of rapidly effecting a conversion of maltose 

 into dextrose ; this is of great physiological significance inasmuch as it 

 points to the probability that the carbohydrates are absorbed from the 

 intestine as dextrose and not as maltose, a view which is supported by 

 the fact that maltose does not appear to be capable of direct assimila- 

 tion, but is excreted largely unchanged if injected into the blood 2 . If 

 this be so then it is as dextrose that the liver receives its supply of 

 carbohydrate material for the formation of glycogen, a fact which is of 

 no small interest when we know that the liver discharges the carbo- 

 hydrate which results from the reconversion of glycogen into sugar as 

 dextrose 3 . (See also sub glycogen.) 



Cane-sugar has been shown by Bernard to be similarly incapable of assimilation ; 

 if injected into the blood it is excreted in the urine unchanged. When taken 

 through the alimentary canal it is probably inverted or converted into a mixture of 

 dextrose and lasvulose which are then assimilable. 



The conversion of hepatic glycogen into sugar as a preliminary to its discharge 

 from the liver has more usually been regarded as dependent upon the activity of 

 some special hepatic enzyme. This view is now no longer tenable in face of the 

 negative evidence as to its existence obtained by more recent observers 4 . (See also 

 sub glycogen.) 



1 Brown and Heron, Proc. Eoy. Soc. No. 204, (1880), p. 393. Liebig's Ann. Bd. 

 cciv. (1880), S. 228. Vella, Moleschott's Untersuch. zu Naturlehre, Bd. xm. (1881), 

 S. 40. Bourquelot, Compt. Eend. T. xcvu. (1883), p. 1000. 



2 Bimmermann, Pfliiger's Arch. Bd. xx. (1879J, S. 201. Philips (Dutch Diss.). 

 See Maly's Bericht, Bd. xi. (1881), S. 60. Dastre et Bourquelot, Compt. Eend. T. 

 xcvin. (1884), p. 1604. Bourquelot, Jn. de I'Anat. et de la Physiol. T. xxn. (1886). 

 p. 161. 



3 Nasse, Pfliiger's Arch. Bd. xiv. (1877), S. 479. Seegen, Ibid. xix. (1879), S. 123. 

 Seegen und Kratschmer, Ibid. xxn. (1880), S. 206. Kiilz, Ibid. xxiv. S. 52. 

 Musculus und v. Mering, Zt.f. physiol. Chem. Bd. n. (1878), S. 417. 



4 Eves, Jl. of Physiol. Vol. v. (1884), p. 342. (Gives litt. to date.) Dastre, 

 Arch, de Physiol. (4) T. i. (1888), p. 69. 



