VARIA TIONS IN PANCREA TIC JUICE. 



553 



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 /2 



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 9 

 <G 



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the zymogen is not soluble in water, thus contrasting markedly with 

 other zymogens. We must regard the existence of a precursor in 

 this case as doubtful, though it is undeniably possible that in the 

 living cell an ante- 

 cedent state of the 

 ferment exists, adapted 

 to storage of the fer- 

 ment ; in that case the 

 mere destruction of the 

 cell might involve the 

 breaking dow r n of this 

 hypothetical zymogen, 

 on account of the pre- 

 cursor of the diastatic 

 ferment being less 

 stable than that of the 

 proteolytic. 



There is also no 

 evidence of any zymo- 

 gen of the fat-decom- FIG. 46. Chart of the course of secretion of pancreatic juice. 

 T^nQinrr favTYiomf -rn'oKn-i The abscissae correspond to hours ; the ordinates corre- 



LllsDJ..L.LcL IUlliJ.t5J.lU, I) IcllY 11. 1 , rt . .. -r-r . -I , . 



n^ n -> i i spond to c.c. of jttice. After Heidenhain. 



Finally, it has been 



found that extracts of pancreas and the pancreatic juice itself 1 have 



the power of inducing a clot in milk, probably by the agency of some 



specific enzyme in the juice. 



The variations in the composition and amount of pancreatic 



juice during digestion. From the earlier experiments of Bern- 

 stein, 2 and those of 

 Heidenhain, 3 it ap- 

 pears that the flow 

 of pancreatic juice 

 has somewhat the 

 following course : 

 Before a meal 

 is over there com- 

 mences a secretion, 

 which reaches a 

 maximum not later 

 than the third hour. 

 Then the secretion 

 sinks to about the 

 sixth or seventh 

 hour, and yet again 

 increases to the 

 ninth or eleventh ; 

 thence it sinks gra- 

 dually to about the 



/ 2 3 f 5 6 73 9 SO tl / 13 14 15 16 1 7 



FIG. 47. Chart of the percentage composition of the flow of 

 pancreatic juice. The abscissae correspond to hours ; the 

 ordinates to percentage of solids. After Heidenhain. 



eighteenth and twentieth. The quality of the juice varies inversely as 

 the quantity. When one rises the other falls. The accompanying 

 diagrams (Figs. 46 and 47) illustrate these variations. 



1 Halliburton and Brodie, Journ. Physiol., Cambridge and London, 1896, vol. xx. 



2 Op. cit. 



3 Hermann's " Handbuch," Bd. v. 



