(1). A method is described by which it is possible
to study feeble action currents.
(2). Various forms of distortion and interference
are discussed.
(3). A complete analysis of the electrical response
of the hen embryo is demonstrated.
(4) . The heart rate throughout the period of incubation has been established under as nearly ideal
conditions as possible.
(5). The earliest record of, electrical response of
the heart of the embryo showed a fast and a slow
component making up a QRST complex.
(6). The electrocardiogram of a 3rd day embryo
was practically identical with that of the adult.
(7). The rate of conduction in the embryonic heart
was very slow.
(8) . Figures are given for the heart rate of the
newly hatched chick during the first three weeks;
these figures are the same as those of the adult.
(9). The newly hatched chick showed remarkable
accelerator action of the sympathetic.
(10). There was little evidence of vagal control in
the chick, but very definite control in the duckling.
(11). Very slight variations in temperature had a marked effect on the heart rate of the embryo and of
the newly hatched chick.
(12). Electrocardiograms and mechanograms were
taken of the Mya heart; a fast and a slow component
was demonstrated.
(13). An unsuccessful attempt was made to record the
electrical response of the Whelk, but the heart
went into systole as soon as it was touched.
(14). The electrical response of the Acanthia
embryo was also recorded.
(15 ). The theory that early embryo hearts gave an
electrical response consisting of a simple wave
which became complex as development progressed, is
discussed, and the curves imitated.
