ON THE IDENTITY OF TRYPSINOGEN AND ENTERO- 

 KINASE RESPECTIVELY, IN VERTEBRATES. Br 

 J. MOLYNEUX HAMILL, M.A., M.B. (Cantab), B.Sc. (Lond.), 

 Sharpey Scholar. 



(From the Physiological Laboratory of University College, London.) 



BAYLISS and S tailing (1) have shown that secretin is not specific 

 for each type of animal but is a definite chemical substance common to 

 all classes of vertebrates. It became of interest, therefore, to ascertain 

 if any similar relationship existed between the pancreatic juice and the 

 enterokinase of different animals, that is to say, whether trypsinogen 

 and enterokinase are specific for each animal or are the same substances 

 throughout the vertebrata. To this end the following procedure was 

 adopted. 



Methods. Enterokinase was prepared from such widely different 

 animals as the dog, cat, rabbit, rat, pigeon, frog, tortoise and fish (dace). 

 The mucous membrane of the upper portion of the small intestine of 

 these animals was lightly scraped, the scrapings ground up with sand 

 and extracted with chloroform water for 36 hours. This extract was 

 filtered, first through paper and then through a Berkfeld filter. A 

 slightly opalescent solution free from all solid particles was thus 

 obtained. 



Pancreatic juice, prepared by the injection of secretin into the 

 jugular vein, a cannula having been previously inserted into the pan- 

 creatic duct, was obtained from a dog, a cat and a rabbit, and was 

 collected in sterilised flasks. To these juices equal volumes of 2/ 

 sodium fluoride solution was added. (In the experiments described 

 below pancreatic juice, or, shortly, P.J., means a mixture of equal 

 volumes of sodium fluoride solution and pure pancreatic juice.) 



A modification of Mett's tubes containing, instead of coagulated egg- 

 albumin, 10/ gelatine dissolved in 1/ sodium fluoride solution and 

 coloured with methyl violet was used to indicate the development of 

 proteolytic activity in the solutions. 



