TRYPSINOGEN. 497 



by the spleen has been repeatedly suggested by SCHIFF/ but this has recently 

 been denied by PRYM. According to this experimenter the extirpation of the 

 spleen causes no change in the properties of the pancreatic juice, and the intra- 

 venous injection of spleen infusion is also without action on a splenectomized 

 dog with permanent pancreatic fistula. The observations of HERZEN that a 

 spleen infusion has a strong activating action upon a weak pancreas . infusion 

 were substantiated by PRYM, Z but he claims that this is due essentially to micro- 

 organsims. Besides this the spleen itself contains proteolytic enzymes (page 

 371). 



The conversion of the trypsinogen into trypsin in the removed gland 

 or in an infusion under the influence of air and water and also by other 

 bodies has been known for a long time. According to VERNON the tryp- 

 sin itself has a strong activating action upon trypsinogen, and in this 

 regard it is more active than enterokinase. The correctness of this 

 statement is still denied by BAYLISS and STARLING and by HEKMA. The 

 ordinary view of HEIDENHAIN, that the transformation of trypsinogen 

 into trypsin is also brought about by acids, has been found to be incor- 

 rect by HEKMA. S Besides the enterokinase and the micro-organisms, 

 there are other activators of the trypsinogen. As first shown by 

 DELEZENNE and then by ZUNZ, by further investigations the lime salts 

 have a special power in activating trypsinogen. 4 These last do not act 

 immediately, but only after some time, for example, a couple of hours, 

 and then they activate suddenly. The lime salts are not necessary 

 for the digestive action of the juice, and when the activation has once 

 taken place, they can be removed without any harm. They probably 

 have a similar action as in the coagulation of the blood. According 

 to DELEZENNE the lime salts have the same importance in the activa- 

 tion of the rennin-zymogen of the juice as in the activation of the 

 trypsinogen. This enzyme is also activated by enterokinase. The 

 erepsin of the pancreatic juice (page 493) occurs as an active enzyme. 



We are not quite clear whether the two other enzymes, the diastase 

 and lipase, are secreted as such or as zymogens. It seems, nevertheless, 

 that both are in part secreted as complete enzymes. 



In the human embryo the trypsinogen and the erepsin (as well as also the 

 pepsin) appear in the fourth and fifth foetal month. The enterokinase appears 

 at the same time or shortly after the trypsinogen. 5 



1 Bellamy, Journ. of Physiol., 27; Mendel and Rettger, Amer. Journ. of Physiol., 7. 

 A very complete reference to the literature may be found in Menia Besbokaia Du 

 rapport fonctionell entre le pankreas et la rate, Lausanne, 1901. 



2 Pfliiger's Arch., 104., and 107. 



3 Vernon, Journ. of Physiol., 28; Hekma, Kon. Akad. v. Wetenschappen te 

 Amsterdam, 1903, and Arch. f. (Anat. u) Physiol., 1904; Bayliss and Starling, Journ. 

 of Physiol., 30 



4 Delezenne, Compt. rend. soc. biol., 59, 60, 62, 63; Zunz, footnote 1, p. 496. 

 6 Ibrahim., Bioch. Zeitschr. 22, 24 (1909). 



