459 
Decrease of the CaCl, percentage 
caused an increased frequency, which was small indeed, but was 
met with in all the experiments. 
A very remarkable fact was that from a certain concentration 
upwards the frequency hardly ever (diagr. I) increased any longer, 
but decreased, and that sometimes rather much. 
When the concentration had arrived at 0, the sinus stopped 
entirely after a shorter or longer time. 
The fact is that the points of the diagrams al CaCl, = 09/) have no right of 
existence. Therefore it should be expressly stated that they were noted down as 
long as it was barely possible to count the contractions or when at least the fluid 
containing no CaCl, had for a long time been driven through the sinus. The 
latter also holds good for the diagrams on KCI (III and IV). 
Number of contr. 
per minute 
0025 005 Q0F5 
Diagram III. Effect of KCl on the frequency of the sinus venosus. 
CaCl, 6 aq. = 0.01 J). 
Number of contr. 
35} per minute ak 
_ 
_ 
ad 
ed 
_— 
0025 005 0075 Ol 0.2 0.3 
Diagram IV. Effect of KCl on the frequency of the sinus venosus. CaCl, (without 
water of crystallization) = 0.01 "/o. 
Moreover some experiments were made on the withdrawal of all 
CaCl, at once. Here too we obtained — though not always - first an 
increased frequency, which was followed by a decrease. 
