1029 
Physiology. — “Contribution to the knowledge of the influence of 
digitalis on the frogs heart. Spontaneous and experimental 
variations of the rhythm.’ By Dr. S. pr Boer. ) (Communi- 
cated by Prof. Dr. G. van RIJNBERK. 
(Communicated in the meeting of November 25, 1916.) ° 
I. Lntroduction. 
It has been proved by. a long series of investigations into the 
influence of digitalis on the frog’s heart, that as a first result of 
the poisoning a slackening of the palpitation sets in, which is not 
a consequence of a stimulation of the Vaguscentra, as paralysis of 
the extremities of the Vagus through atropine does not prevent this 
slackening. It was moreover found that an increase of the size of 
the systoles sets in after the poisoning. In the second stage of the 
poisoning an irregular activity of the heart occurs, followed by a 
stagnation of the ventricle in a maximal condition of contraction. 
Afterwards the stagnation of the auricles follows. 
Boum?) discovered that after the poisoning of the frog’s heart 
with digitalis the systolic emptying increases in completeness, so that 
at the highest point of the systole the ventricle is white, a proof 
that the contents have been removed to the last drop. Suddenly the 
number of palpitations can be reduced to half the usual number, 
a halving of the rhythm of the ventricle, which is still repeated once 
or twice, till at last the ventricle stands still in systole. Then the 
auricles still continue to pulsate for a considerable time. Bonm 
ascertained moreover that the irregularities of the heart-rbythm 
caused by poisoning with digitalis, disappear by stimulation of the 
Vagus. 
WrBAuw®) obtained similar phenomena after poisoning with helle- 
boreine: decrease of the frequency of palpitation, increase of the 
volume of palpitation and the activity of the heart in the first stage 
of poisoning; during the second stage of this process irregularities 
took likewise place, till at last the heart stood still in systole. 
After washing the poison out the phenomena of poisoning could 
recoil again, whilst repeated poisoning occasioned a repetition of 
these phenomena. 
By Hepsom‘) and Straus‘) similar disturbances of rhythm of the 
1) This investigation was made in the Physiological Laboratory at Amsterdam. 
2) Priiigers Archiv. Bd. 5. 
3) Archiv f. exper. Pharmakol. Bd. 44. 
4) Archiv f. exper. Path. u. Pharm. Bd. 45, 1901, Seite 317. 
5) Archiv f. exper. Path. u. Pharm. Bd. 45, 1901, Seite 346. 
