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Physiology. — “The electrocardiogram of the foetal heart” By 
Prof. J. K. A. WERTHEIM SALOMONSON. 
In 1906 Cremer published an electrocardiogram of a human 
embryo in utero, taken in a healthy woman during the last period 
of pregnaney. The curve showed oscillations caused by the heart of 
the mother, between which less conspicuous deviations could be seen, 
caused by the foetal heart-action. These latter had the form of 
monophasic deviations, but probably they should not be considered 
as a true representation of the actual electrical potential differences. 
CreMER’S investigations were repeated by Foa, who was not able 
to extend our knowledge in this respect and could only confirm 
CREMER’S statement. 
I have tried to get some further insight in the peculiarities of the 
foetal electrocardiogram by investigating it in the embryo of the 
chicken. This very obvious way was clearly indicated, as ZwAARDE- 
MAKER had shown that an electrocardiogram could be taken from 
partly-hatched eggs. He published a foetal electrocardiogram in his 
Treatise of Physiology. . 
Though my researches on this subject were commenced about a 
year ago and are not yet completed owing to a lengthy interval 
during the autumn and winterseasons, | may be permitted to show 
some of the results of my experiments. 
Long before the conclusion of the first 60 hours of the incubating 
period, we can see in the chicken’s embryo a strongly pulsating 
tubular heart, slightly curved to an s-form. In this early condition I 
have not been able to register any electrical potential difference *). 
The reason is that probably at that time the potential differences 
caused by the heart beats are exceedingly small. The electrical resis- 
tance of the substance in which the foetal heart is embedded and 
which contains albuminous. and fatty matter is rather high. This 
combination of a low potential difference acting on a high resistance 
makes it very difficult even with an instrument so delicate as the 
string-galvanometer to detect the potential difference. The string- 
electrometer gave me no better results. 
In the end of the first week we can generally without any par- 
ticular difficulty lead off electrical oscillations from the foetal heart. 
These are very regular, isochronic with the heart beats, and show 
a simple monophasic deviation. Generally the ascending part has a 
slighter slope than the descending part. The descending part is fol- 
lowed immediately, without an isoelectric interval, by the next 
1) | have since succeeded in doing so. 
