THE FACTS COLLECTED IN THE THIRD PART OF THIS PAPER JUSTIFY THE FOLLOWING CONCLUSIONS: (1) All of the cardinal symptoms of Stokes-Adams disease may be duplicated by heart-block resulting from a lesion in or near the auriculo-ventricular bundle of His, and by this alone. (2) No typical case of Stokes-Adams disease has been described in which heart-block might not have been the cause of the trouble. (3) It can be shown that all cases of Stokes-Adams disease which have been studied by sufficiently accurate methods were cases of heart-block. (4) It would appear that heart-block without and with syncopal attacks are two stages of the same disease process.