. Electricity : its medical and surgical applications, including radiotherapy and phototherapy . Profs. E. B. Twitmyerand C. K. Mills, of the University of Pennsyl-vania, have devised a convenient instrument (Fig. 119) for use whengreat accuracy is desired in the examination of temperature sense. Itdepends upon the power of the galvanic current to generate heat,which, of course, becomes greater or less as the current from thebattery is made stronger or weaker. The amount is measured by thethermometer seen in Fig. 119. The development of electric currents by contracting muscle (p. 106)has been
. Electricity : its medical and surgical applications, including radiotherapy and phototherapy . Profs. E. B. Twitmyerand C. K. Mills, of the University of Pennsyl-vania, have devised a convenient instrument (Fig. 119) for use whengreat accuracy is desired in the examination of temperature sense. Itdepends upon the power of the galvanic current to generate heat,which, of course, becomes greater or less as the current from thebattery is made stronger or weaker. The amount is measured by thethermometer seen in Fig. 119. The development of electric currents by contracting muscle (p. 106)has been utilized recently as an aid in the study and diagnosis of faulty 180 DISORDERS OF THE SENSORY TRACT cardiac action.^ By means of the very sensitive galvanometer devisedby Prof. Einthoven, tracings are made which differ in certain diseasedconditions from that obtained in a healthy person. Fig. 120 AURICULAR. Diagram showing the time relations between the waves of the electrocardiograms, the heartsounds, and the contractions of auricles and ventricles. The short interval between the beginningof the R wave and the beginning of the rise in the intraventricular pressure is interpreted by Kahnas due to the phenomena of conduction within the heart. In experimental ventricular extra-systoles the electric and mechanical changes are absolutely synchronous. Vertical divisions indi-cate tenths of a second. (Barker, Hirschfelder, and Bond.) Figs. 120 and 121 show normal tracings. The first wave, P, is dueto activity of the auricle, the large wave R is due to the contraction Fig. 121 4
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