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the gas-chamber the atria begin to recover and after 39 minutes! 
the electrical phenomena reach their original size again with their 1 
mechanical changes. Such poisoning-experiments can be repeated a few I 
times without any great harm for the sample-object. 
It is striking how the right atrium every time recovers first 1 
from the poisoning, and only later the left atrium begins to show! 
mechanical changes. If the electrogram is examined during and after | 
the poisoning, it is remarkable that the general form is not really! 
altered here, but that the amplitude of the tops is greater than after f 
the recovery of the poisoning, whilst the mechanical changes are i 
altered in exactly the other way. 
The form of the atrio-electrogram is evidently also dependent on! 
nervous influences. Einthoven and Vaandrager have already directed® 
attention to this for the cardio-electrogram of a dog derived indirectly, I 
For the atria of Emys this may be proved very distinctly at direct ! 
derivation under the influence of vagus-stimulation. 
A heart of Emys derobed of ventriculus, so consisting only of ; 
the sinus and the two atria, is derived to the string-galvanometer. 
Derivation of one of the two atria separately or combined makes 
no particular difference. Therefore the derivation in the experiment 
takes place from sinus and right atrium-top. The right n. vagus in 
the neck is prepared free. The electrogram shows a fine double- 
topped image, accompanied by regular mechanical changes. At 
stimulation of the right n. vagus with induction-currents the mechanical 
utterance undergoes alterations. After a last contraction of the sinus, 
showing itself in a slight elevation in the myogram of the atria 
there begins for the object a vagus-standstill, which, as soon as the 
stimulus is put a stop to, is broken off and causes a new series of 
atrium-contractions with a strong sinus-contraction. During the vaguS- 
standstill the object has produced no electrical phenomena that are 
to be registered. Directly after the vagus-standstill the atrio- 
electrograms show themselves again, but now altered in form. The 
double-topped image has been replaced by a phenomenon with a 
strongly pronounced diphasic character, which however, the stimulation 
being stopped, passes into the original double-topped image by a 
gradual alteration. In this experiment the s n. vagus was stimulated by 
means of the sledge-inductorium of mi Bois Reymond, without a 
kernel, at a secondary coil-distance of 5.5 cm. and a LEssiNG-element 
in the primary chain. 
When weaker currents are used for stimulation, a state of things 
may be obtained in which the vagus-standstill does not appear, but 
in which the peculiar alterations in the form of the electrogram of 
