The Activation of Pancreatic Extract. 



129 



the thickness of the sac, results may be obtained varying from 

 total retention to complete passage of the active substance. 



81 (491) 



The activation of pancreatic extract. 



By A. R. DOCHEZ. 



[From the Laboratory of the Rockefeller Institute for Medical 



Research.'] 



Many years ago Heidenhain demonstrated that the pancreas 

 does not contain trypsin in an active form, but that it exists in the 

 pancreatic tissue as a proferment or zymogen. Heidenhain was 

 able to convert pancreatic zymogen into active trypsin by treating 

 pancreas with weak acids. This fact was later confirmed by other 

 investigators. Hekma, who used pancreatic juice obtained from a 

 fistula, observed that the trypsinogen of the juice cannot be activ- 

 ated by treatment with acid. In 1899, Pawlow and Schepowalni- 

 kow discovered, in the mucosa of the small intestine, a specific 

 substance which converts trypsinogen into active trypsin, and 

 which activates both pancreatic extract and pancreatic juice. Ver- 

 non, in a series of papers published in 1901 and 1902 studied the 

 activation of trypsinogen. His observations were largely upon 

 pancreatic extract, although in some instances he used pancreatic 

 juice. His conclusions are as follows : fresh pancreas shows no 

 enzymotic activity ; upon standing a few days extracts suddenly 

 develop nearly their maximal tryptic activity ; the addition of small 

 quantities of active pancreatic extract increases enormously the 

 rate of conversion of zymogen into active enzyme ; fresh pancreas 

 treated for twenty hours with 0.2 per cent, acetic acid develops 

 active trypsin. Using dog's pancreatic juice, Vernon claims that 

 one per cent, active pancreatic extract liberates three times more 

 trypsin than one per cent, succus entericus. The same result is 

 obtained with glycerine extract of fresh pancreas. Bayliss and 

 Starling, who worked with large quantities of exceptionally pure 

 pancreatic juice, contradict Vernon's results upon the activation of 

 pancreatic juice by any other agent than the enterokinase of suc- 

 cus entericus. They were not able to activate the trypsinogen of 

 the juice with active trypsin, or by means of any simple chemical 



