This case which is an interesting contribution to the study of the psycho-motor centres is an example of an old encapsuled nodule in the left hemisphere, resulting from a lesion in childhood, which destroyed the superior parietal convolution, and produced atrophy of the superior portion of the postcentral and para-central convolutions. The right leg was paralysed, but regained its function to a certain extent, while the right arm became completely useless. The paralysed extremities atrophied. There was atrophy of the right lateral and of the left anterior columns of the spinal cord. Descending degeneration of the pyramidal tracts.