抄録
1. In an anatomical study of the toad's sinus venosus, it was found that the muscle fibers are not homogenously distributed. The main muscle strands started from a point situated about3mm. above the left hepatic vein. It formed the fan-like tissue (Uchiyama).
2. By using a small heating thermode, various parts of the sinus venosus were heated locally. The highly thermo-sensitive region was found to coincide with the sites of Remark's ganglia.
3. After the removal of ganglia or the application of nicotine, localized heating of the sinus venosus failed to cause tachycardia.
4. The possible relationships between the thermo-sensitive region and the localization of the cardiac pacemaker are discussed.
