The string galvanometer, which consists of a metal fiber stretched between two magnets, was originally developed by French engineer Clément Adair in 1872 to send telegrams.Įinthoven’s EKG work has now been commemorated with an IEEE Milestone. The technique has its origins in the work of Willem Einthoven, who in 1905 used a string galvanometer to conduct the first recording of a human electrocardiogram (EKG). Among these I find that a heart in a state of depression is greatly stimulated by extracts pf Abroma augusta.THE INSTITUTE For more than 100 years, doctors have relied on electrocardiography to measure the heart’s electrical activity. I have recently been engaged in investigating the action of various medicinal plants of India on the activity of the animal heart. Dilute solution of potassium bromide causes a depression of cardiac pulsation this depression is removed by the physiological antagonism produced by certain drugs. The effect of drugs is often remarkably similar in the two cases. In both, application of external stimulus has no effect during systolic phase of contraction, whereas an extra-pulsation is produced by stimulus during the diastolic phase of expansion. The rhythmic tissue in animal and plant, has a long refractory period. Diminution of internal pressure causes an arrest in both. Rise of temperature up to an optimum, on the other hand, enhances the frequency. In both, lowering of temperature slows down the pulsation culminating in an arrest. I have demonstrated elsewhere the remarkable similarity of rhythmic mechanism in animal and plant. Similarity of Rhythmic Mechanism in Animal and Plant In the particular specimen of frog the total period is represented by 14 dot-intervals or 0.7 second, while in the fish it is 16 dot-intervals or 0.8 second. The total period is 34 dot-intervals, or 1.7 seconds. The period of a complete cycle is much longer in tortoise. The records show the auricular contraction preceding the ventricular. The time-relations, it is to remembered, is found from the intervals of successive dots 1 / 20 second apart. The writing lever was tuned to vibrate 20 times in a second, the magnification produced being about 8 times. The cardiograms of different animals show, moreover, certain characteristic differences in regard to time-relations, as illustrated by records of tortoise, of frog and of Ophiocephalus fish given below. The systolic contraction and its persistence, the diastolic expansion and the subsequent pause, and any variation of these under external agencies, can thus be quantitatively determined. The Resonant Cardiograph inscribes the different phases of the heartbeat with unprecedented accuracy. The Characteristics of Cardiac Pulsation. The difficulty has been overcome by the writer being thrown into resonant vibration in The friction of the writing point against the smoked glass surface, however, introduces serious error in the accurate record of the amplitude and time-relations of the response-curve. The response of Mimosa is recorded by means of a writing lever suitably attached to the leaf (fig. The time-interval between stimulus and response will now be longer than under direct stimulation the latent period of the pulvinus and the length of transmission afford sufficient data for the determination of the velocity of excitatory impulse in the plant, which I have shown elsewhere, is analogous to the nervous impulse in the animal. If instead of direct stimulation of the pulvinus, stimulus be applied on the petiole at a certain distance from the motile organ, then an excitatory impulse is transmitted through the intervening distance. The lost time between the incidence of stimulus and the beginning of responsive movement is designated as the Latent Period. After the completion of the fall of the leaf the contracted pulvinus slowly recovers as seen in the re-erection of the leaf. When the sensitive pulvinus of Mimosa pudica is directly stimulated, say by an electric shock, a responsive contraction and fall of the leaf is initiated after the lapse of a short interval. This is specially so in the measurement of time relations of different phases of response of living tissues. The exact determination of extremely short intervals of time is an important problem in various investigations.
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