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modification of the Ca-ion-concentration, because the [HCO',| and 
[Ca] are inversely proportional to each other, the influence of this 
modification is great, as appears from the following examples: 
a. Perfusion with NaCl 0,6 °/,, KCl 0,02 °/,, CaCl,.6 aq. 0,04°/,, 
NaHCO, 0,05 °/,. Pir — 8,6. After 5 minutes the spontaneous con- 
tractions have disappeared and the stomach is contracted spastically : 
no effect of vagus-irritability is visible. 
6. Perfusion with NaCl 0,6°/,, KCI 0,02 °/,, CaCl,.6 aq 0,04°/,, 
NaHCO, 0,10°/,, Pa = 8,6. After 10 minutes the stomach is contracting 
with intense spasms, especially the pyloric part of it. The vagus is 
extremely irritable, at 15 em’s coil-distance deep waves arise in the 
stomach-wall which last very long and are displaced very slightly ; 
finally we have a very spastically contracted stomach (pylorospasmus). 
c. Perfusion with NaCl 0,5 °/,, KCl 0,02 °/,, CaCl,. 6 aq 0,04 °/,, 
NaHCO, 0,15 °/,, Po = 8,6. After 10 minutes the stomach shows 
very slight peristalsis with intense spastic contractions in the pyloric 
part. Vagus-irritability at 12 cm, tonic contractions lasting a very 
long time. 
d. Perfusion with NaCl 0,5 °/,, KCl 0,02 °/,, CaCl,. 6 aq. 0,04 °/,, 
NaHCO, 0,20°/,, Pa= 8,6. With this liquid the spontaneous perist- 
altic movements appear again; the vagus is irritable at a coil-distance 
of 9 cm. and produces a series of peristaltic movements; the spastic 
contractions are still present in a slight degree. 
e. Perfusion with NaCl 0,5 °/,, KCl 0,02 °/,, CaCl,. 6aq. 0,04 °/,, 
NaHCO, 0,28 °/,, Po = 8,6. With this liquid the vagus is irritable 
at a coil-distance of 7 cm.; there are normal peristaltic movements 
and no spastic contractions. The conditions are completely like dose 
of the unperfused stomach. 
From these experiments appears clearly the great influence which 
a change in bicarbonate-concentration has on the irritability of the 
n. vagus and on the spontaneous rhythmical movements of the 
stomach-wall. The latter effect is probably also due to the influence 
on the autonomous plexus of AurrBacH. It cannot be decided with 
certainty whether we have to think here especially of a direct 
influence of the HCO,-ions *) or only of the influence of the latter 
on the [Ca™], but, in connection with the experiments with pure 
NaCl + CaCl, solutions, the primary significance of the Ca-ions seems 
to us by far the more probable. 
We attach some significance to the fact that a decrease of | HCO,’], 
1) Rona and NeukKircH: Pfliiger’s Archiv. 148, 285, 1912. 
