An introduction to physiology . the Heart Nerves It has been shown that the heart receives in-hibitory and augmenting nerve fibres. The sit-uation of the inhibitory and augmenting centres,i. e., the nerve cells from which the inhibitoryand augmenting fibres spring, should now beconsidered. Inhibitory Centre. — Place a frog and a smallsponge wet with ether under a glass jar. Be very INNERVATION OF HEART AND BLOOD-VESSELS 565 careful not to kill the frog by an overdose ofether. When insensibility is complete, place theanimal, back uppermost, on a frog-board. Cut through the skin in the median li
An introduction to physiology . the Heart Nerves It has been shown that the heart receives in-hibitory and augmenting nerve fibres. The sit-uation of the inhibitory and augmenting centres,i. e., the nerve cells from which the inhibitoryand augmenting fibres spring, should now beconsidered. Inhibitory Centre. — Place a frog and a smallsponge wet with ether under a glass jar. Be very INNERVATION OF HEART AND BLOOD-VESSELS 565 careful not to kill the frog by an overdose ofether. When insensibility is complete, place theanimal, back uppermost, on a frog-board. Cut through the skin in the median linefrom the nose about halfway to the urostyle. Care-fully uncover the roof of theskull. Eemove the longitu-dinal muscles on either sideof the 1st, 2d, and 3d verte-bras. Strip off the parietalbones with forceps, begin-ning at the anterior end,opposite the anterior marginof the orbit. Clear awaythe occipital bones. Sawthrough the laminae of thefirst three vertebrae, and re-move the laminae to exposethe spinal cord. Expose the. Fig. 74. View of the brainof a frog from above, en-larged. Olfactory lobes,heart by Cutting away the Cerebral hemispheres. Pineal body. chest wall over the pericar-dium. Hold the frog in sucha way that the heart can beobserved while the brain andcord are stimulated. Withneedle electrodes, the points of which should be Optic thalami. Opticlobes. C Cerebellum. oblongata. rhomboidalis. (AfterFosters plate in Bunion-Sandersons Handbook.) 566 THE OUTGO OF ENERGY one millimetre apart, stimulate the spinal cordwith a tetanizing current of a strength easilyborne on the tongue. Stimulation of the spinal cord will not inhibitthe heart. Stimulation of the cerebral hemi-spheres will be also ineffectual. Now stimulatethe medulla oblongata. (Fig. 74.) The heart will be inhibited. This method of locating the cardio-inhibitorycentre is unsatisfactory, because the inhibitionproduced may possibly be the result of the stim
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