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NaCl 0.6°/, + KCl 0.02 °/, (Py—= 8.6). The following experiments 
give a brief survey of it: 
a. unperfused stomach, vagus-effect at a distance of 8 em., after- 
wards NaCl 0.6 °/, + KCl 0.02 °/,; after 10 minutes the vagus is 
un-irritable, the stomach is limp. Then NaCl 0.6°/,, KCl 0.02 °/,, 
CaCl, .6 aq 0.002 °/,; vagus-effect still fails to appear, stomach 
remains limp, though somewhat less so than when it is perfused 
with a pure NaCl solution ; 
6. unperfused stomach, vagus-effect at 7.5 em., then NaCl 0.6°/,, 
KCI 0.02 °/,; after 15 minutes the stomach is limp, stimulation of 
vagus has no effect. Then NaCl 0.6 °/,, KCI 0.02 °/,, CaCl,.6 aq 
0.004 °/,. Whereas the effect of this Ca-concentration on the perfused 
heart is clearly visible, there is no effect whatever on the stomach, 
except a slight tonie contraction. 
c. Nor could a return of the vagus-irritability be established in 
numerous perfusions, when to the NaCl 0.6 °/, + KCl 0.02 °/, was 
added respectively CaCl, .6 aq 0.006°/,, 0.008°/,, 0.010°/,, ete. But 
d. the addition of 0015°/, CaCl, .6 aq to NaCl 0.6°/,+ KC10.02°/, 
caused the vagus-irritability to return completely. We must, however, 
stress the fact, that, to obtain this result, one should take special 
precautions. As namely the liquid does not possess at all a buffer- 
system against H-ions, fluctuations of [H°] occur very easily. It is 
necessary that the Py of this perfusion-liquid should be 8.6 and 
remain constant during the experiment. The use of a rubber tube 
is very dangerous in this experiment, as it nearly always makes 
the liquid too acid. 
These precautions being taken, one can always demonstrate that 
a concentration of 0.015 °/, CaCl, .6 aq (and also 0.016 °/,) is able 
to balance the concentration of alkali-ions; this concentration corre- 
sponds to a free [Ca] of about 9 milligrammes per litre. 
It is an interesting fact that exactly the same concentration of 
Ca-ions proved necessary for the preservation of the impermeability 
of the glomerulal membrane for physiological quantities of glucose.') 
e. a concentration of CaCl,.6 aq of 0.020°/, and higher con- 
centrations are unable to preserve or recall the vagus-irritability ; 
then tonic contractions of the stomach-wall too disappear again 
completely iu this case. 
4. The influence of a concentration of hydrogen-ions. 
By choosing the total quantity of Ca of the perfusion-liquid in 
1) HAMBURGER and BRINKMANN, l.c. 
