the ventricle was carefully turned up and, if necessary, fixed by a 
piece of wadding. 
The parietes of the sinus then lying bare were taken with a 
small “serre fine’, which transmitted the contractions by means of 
a very light lever to the sooted paper, so that they were magnified 
about ten times. Special care was taken that the other parts of the 
heart should either not modify the curves at all or modify them 
but slightly. This can be done very easily. 
As a perfusion fluid I used a solution of RiNGer containing: 
0,6 °/, NaCl, 0,0075 °/, KCI, 0,01 °/, NaHCO,, whilst the CaCl, per- 
centage was in the first experiments 0,01 °/, CaCl, 6 aq. and after- 
wards 0.01 °/, CaCl, without crystallization water: that is about 
twice as much. [The CaCl, solution obtained by weighing the 
crystallized salt was titrated afterwards). This fluid was gradually 
modified in accordance with the nature of the experiments. The 
percentage of NaHCO, remained the same, however, to prevent 
changes into Hand OH’. 
The deviations obtained on the sooted paper varied from | to 5 
millimetres and were also during the experiments highly variable, 
thus forming a contrast with the frequency. The latter decreased a 
little at first, but when the heart had onee become hypodynamic, 
it remained surprisingly regular; also when after a series of other 
fluids, the original solution was taken again, the frequency returned 
entirely or almost entirely to its former value. 
In this connection it may be noticed that for the heari-action the auto- 
matism of the auricle is of much greater importance than its contractility. 
Tonus-flactuations have been observed but seldom. 
CaCl,. 
The diagrams I and II relate to the experiments with CaCl,. 
Number of contr. p. min. 
i 
f 
_—. 
~. 
Meee. 
Sr en a 
0,05 01 , 05 
Diagram I. Effect of CaCl, on the frequency of the 
sinus venosus; dose from 0 to 0.5 9/9. 
