Study of feeble bio-electric currents by means of thermionic valve amplification

Abstract

(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.