( 694 ) 
experiments were made on the isolated heart. The heart was 
perfused with 0.9°/, NaCl (Kouniasko), then with derrid-salt-solution 
(1 : 1.000.000—1 : 30.000). First the ventricle, in later experiments 
also the auricle, was registered. Slowing of the pulse now showed 
itself again, dependent on the effect on the motor apparatus of the 
heart itself, for if atropin was added to the solution or dropped on 
to the heart, the slowing of the pulse was not neutralised, neither 
was it prevented. When the suspension method of auricle and ventricle 
was applied, it appeared that there was absence of every second 
ventricle contraction. I have not observed complete paralysis, nor 
when larger doses were administered. 
In frogs the influence on the heart was also examined. After the 
above-mentioned injections the last symptom was heart-paralysis. 
Further experiments were made on the heart either isolated, or in 
situ perfused by a cannula tied in the sinus, or excised and attached 
to the Straub cannula’) so that it could go on beating unchanged 
for hours by means of Ringer solution (2 cc). If after the normal- 
period derrid was added, slowing of the pulse and irregularities 
showed themselves as before; at last the heart stopped in diastole. 
If for checking-purposes only 0.6°/, NaCl or Ringer’s solution besides 
corresponding quantities of alcohol were added, this did result in 
slowing of the pulse and weakening of the heart, but never in 
irregularities if these had not manifested themselves from the beginning. 
If then derrid was added the irregularities appeared. Experiments 
were also made on the heart in situ; here a cannula was tied in 
the vena cava inferior through which the solution was admitted ; 
the animal had been decerebrised and curarised beforehand. Ventricle 
and auricle were registered. Here also slowing of the pulse could be 
observed, besides absence of ventricle-systole, paralysis of the auricle 
and all kinds of irregularities. Destruction of brain and spinal cord, 
besides atropin, did not influence these symptoms. During a sub- 
sequent series of experiments ventricle and auricle were connected 
with the inductor and stimulated faradically and by single break 
induction shocks. Then it appeared that the refractory period of the 
ventricle was lengthened; the time of conduction from auricle to 
ventricle did not show any perceptible change. 
Consequently the influence of derrid on the heart of frogs is a 
negative chrono-, bathmo-, and tonotropic one. The irregularity of 
the pulse, especially the absence of ventricle-systole and of every second 
1, W. Srraus. Die Wirk. des Antiarins am ausgeschnittenen, suspendierlen 
Froschherzen. Schmied arch. 1901. nr. 45, s. 346. 
