792 PHYSIOLOGY 



its function of protein hydrolysis at the upper part of the gut and 

 is destroyed before reaching the lower end. 



THE ACTIVATION OF PANCREATIC JUICE 



It was observed by Kiihne that extracts of the fresh pancreas 

 did not develop their full activity for some considerable time, the 

 development being aided by preliminary treatment with a weak 

 acid. When a pancreatic fistula is made according to Pawlow's 

 method, the juice obtained always presents some proteolytic activity. 

 It was shown by Pawlow and ChepowalnikofE that the development 

 of the activity of the juice was due to the action of a constituent 

 of the succus entericus which they named enterokinase, and it has 

 since been found that if care be taken to avoid contact of the juice 

 with the mucous membrane surrounding the orifice of the duct, it 

 is, when secreted, entirely inactive. Pawlow regarded the entero- 

 kinase as acting like a ferment on the precursor of trypsin, namely, 

 trypsinogen, present in the juice as secreted. He named this body 

 therefore the ' ferment of ferments.' This view of the action of 

 enterokinase has been challenged, especially by Delezenne, according 

 to whom there is an actual combination between the enterokinase 

 and the trypsinogen, trypsin itself being a mixture or combination 

 of the two bodies. He compared their action to that of the ha3mo- 

 lysins, which, as is well known, involve in their action the co-operation 

 of two bodies, the amboceptor and the complement. If this w T ere 

 correct there should be always a proportionality between the quanti- 

 ties of trypsinogen and enterokinase respectively which are necessary 

 to form trypsin. It has been shown by Bayliss and Starling that 

 this proportionality is not present. The smallest quantity of entero- 

 kinase is sufficient to activate any amount of trypsinogen if sufficient 

 time be allowed. The effect of increasing or diminishing the 

 amount of enterokinase is not to alter the total amount of trypsin 

 finally produced, but merely the time taken for its production. This 

 behaviour characterises a ferment, and we may therefore conclude 

 that the view originally put forward by Pawlow is correct, namely, 

 that trypsin is produced from trypsinogen under the action of a 

 ferment enterokinase. This is not the only method by which the 

 conversion of trypsinogen into the active ferment can be brought 

 about. If pancreatic juice be allowed to stand, even with the addition 

 of toluol to prevent bacterial infection, it gradually acquires a certain 

 degree of activity. If, however, sodium fluoride be used as an 

 antiseptic the juice remains permanently inactive. The spontaneous 

 activation of the juice may be hastened by neutralisation. The 

 most potent means next to enterokinase is the addition of lime salts. 

 If a few drops of 10 per cent, calcium chloride solution be added 



