File:American journal of physiology (1898) (14782253515).jpg

Identifier: americanjourna28ameruoft (find matches)
Title: American journal of physiology
Year: 1898 (1890s)
Authors: American Physiological Society (1887- ) American Physiological Society (1887- ). Abstracts of papers presented at the fall meeting American Physiological Society (1887- ). Proceedings
Subjects: Physiology Physiology
Publisher: (Bethesda, Md., etc.) American Physiological Society (etc.)
Contributing Library: Gerstein - University of Toronto
Digitizing Sponsor: University of Toronto

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rogressive one, but progressive, i. e., toward the heart.The exsected portion which includes that portion of the heart inwhich the former cardiac rhythm was initiated is found beating atthe original rate. Fig. 3 shows the result of such an operation. Ais a tracing of the normal heart rate; the tracing lever was attached tothe ventricle. 5 is a tracing of the same preparation made after theright veins had been tied off; this procedure changed the rate of theheart to approximately one fourth its previous rate, although it was RJiythmicity in the Turtle^s Heart. 335 easily seen that the beat still originated at the base of the heart andin fact in the veins of the left side. In C the right veins had been cutaway, thus eliminating the conspicuous tug effects of the rightveins. The right vagus is noted to have lost its effect in 5 as a resultof the ligature, but the left vagus, which previously had been foundto have no chronotropic effect, is now noted to be active; the dis- A B C L III f^^
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Figure 3. — About one half the original size. Tracing by suspension method of ven-tricular contractions. A = normal heart, B = after tying off the right caval veins,C = after cutting away the right caval veins the tug of the right veins noted in Bdisappears in C. The effect of stimulation of the vagi before and after clampingthe right veins is shown; at R and R the right vagus nerve was stimulated and at Lthe left vagus was stimulated. cussion of the vagus effects will be deferred to another portion of thispaper. In several experiments a transverse cut was made at the sino-auricular junction and auricles and ventricles were removed fromthe body. The veins of the right and left side with the sinus be-tween them formed a transverse beating strand in which the wavewas seen passing from right to left with the original rhythm of theheart. If a median section should be made, we should have (exceptfor the adhering bits of the sinus) the same condition as that in thefirst experiments consid

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