100 
\ 
With regard to potassium we can say that the ratios Cxer and 
P Cnaci 
EOL must be constant. 
Coacl, 
Though J. Lore was the first to make a thorough investigation of 
the whole subject of the antagonism of salts‘), Ringer had already 
then made out that the salts in blood serum must, in their coneen- 
tration, stand to one another in a definite proportion. He demonstrated 
at the same time that this also applies to rubidium chloride which 
may in every respect take the place of potassium chloride.*) — I 
have succeeded in detecting a new group of salts that can replace 
the potassium constituent of Rincrr’s mixture, demonstrating at the 
same time their antagonism to the other constituents. — I experi- 
mented upon the hearts of Rana temporaria, Rana esculenta and 
Anodonta. fluviatilis. 
The heart of the frog was exposed after the destruction of the 
central nervous system; then an incision was made in the sinus and 
the septum atriorum was destroyed. A KRONECKER cannula was inserted’) 
and ligatured to the atrium. When the heart was thus tied to the 
cannula and was completely removed from the body, the cannula 
was connected to the circulating apparatus. This apparatus was 
composed of some flasks after Mariotrr, each containing one of the 
liquids to be uséd and each communicating singly with the cannula 
through the tube. Clamps were applied to enable us to send the 
liquids separately through the heart. The tubes were as short as 
could be, in order to observe directly the changed action of the 
heart with every separate circulating fluid. This enabled us also 
to approximate the time required by the heart for its reaction on 
any of the circulating fluids. The pressure was in this case main- 
tained at 90 mm. while the mean temperature was 13° C. 
By suspending the ventricle the contractions were registered on 
a kymographion. 
In preparing the liquids used we started from a mother solution 
consisting of 
aq. dist. 1000.— 
chloret. natric. 1.— 
chloret. calcic. 0,2 
bicarb. natric. 0,2 
glucose 1.— 
') J. LoeB in G. Oppennermer, Handb. der Biochemie Vol. Ila p. 104. 
*) Journal of Physiol. Vol. IV p. 370. 
5) Tigersrept, Lehrbuch der Physiol. des Kreislaufes 1893 p. 154. 
