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TRYPSINOGEN. 497
by the sploon has beeti repeatedly suggested by Schiff, 1
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, 2
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.3
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 fcetal 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.
s
Ibrahim., Bioch. Zeitschr. 22, 24 (1909).
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