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Physiology. — “A study of the heartmuscle according to the 
pharmaco-physiological method.” By Dr. S. pr Borr. (Com- 
municated by Prof. G. van RIJNBERK). 
(Communicated in the meeting of March 25, 1916). 
Introduction. When studying the function of the heart we can 
do so in the first place according to the usual physiological methods. 
In the second place we can examine the heart according to the phar- 
macological method by making poisons exert influence upon it. We 
derive the knowledge of the disturbances of the heart-rhythm espe- 
cially from the use of such poisons as incite the heart-muscle to 
greater activity, consequently the poisons of the groups digitalis, 
antiarine and veratrine. All these poisons, if not applied in too great 
a dose, cause an increase of the dimension of the systoles, after 
which suddenly halving of rhythm can occur. This was shown by 
Borum (1) for digitalis, by v. Brzor.p and Hirt (2) and also by 
Boerum for veratrine, by HepBom (4) and Straus (5) for antiarine. 
This halving of the rhythm was caused by an increase of the dura- 
tion of the refractory period and at the same time of the a-v-interval. 
It took first place at the ventricle and afterwards at the auricle. 
At last the heart stood still in maximal systole. I refer for my own 
investigations into the modifications of the heart-rhythm to the list 
of literature at the conclusion of this communication (6, 7, 
and 8). 
Besides these physiological and pharmacological methods the com- 
bined pharmaco-physiological method can, in my opinion, be of 
great use for the study of the general physiology of the heart. I 
understand by this the application of tbe usual physiological methods 
to the poisoned heart, in consequence of which the irritability, 
conductivity and contractility have changed. I applied this method 
already previously, when by refrigeration of the sinus venosis I 
reduced the ventricle of a frog’s heart, pulsating, after being poisoned 
with veratrine, in the halved ventricle-rhythm, to the normal rhythm. 
At the same time I made some investigations into frog’s hearts 
poisoned with veratrine by means of extra-stimulation. In this way 
I could reduce a ventricle, pulsating in the halved rhythm, to the 
normal twice as rapid rhythm, by an extra-stimulation at the end 
of the diastole. I have now systematically applied this method, i.e. 
the application of extra-stimulations during the different time-moments 
of the heart-period of hearts poisoned with veratrine, and obtained 
in this way a rich material of curves. I arranged my experiments, 
