Convulsions were caused in cats by metrazol injection. The parts between the inner capsule and brain leg were lesioned in many directions with synchro-symmtero-encephalotome within 12 seconds after the onset of convulsions. The changes of convulsions were continously recorded and studied using an electromyogram. 1) The lesions in both side and in upper parts brought no stop of convulsions. 2) At lesion in lower parts, we found the stop of convulsions in 1/3 cases and that in inferolateral parts 1/2 cases. In others no changes were seen. 3) At the lesion in superolateral parts there was the stop of convulsion in only few cases. 4) In the lesions mentioned above no important propagating ways of convulsions were fonnd. 5) At the lesion in the central part the convulsions do not stop at the upper half but stop when it comes to the upper part of pyramidal way in the lower half. 6) The parts in which main propagating ways are found are at the lower half of the central part. 7) Consequently the pyramidal fiber is not important to the propagating of convulsive excitment.