The cells of the reticular formation are known to be connected with the nerve nuclei, on the one hand, and with longitudinal fasciculi, which, since they run into the cord, terminate either in the grey matter or the nerve roots directly, for nerve fibres do not terminate with, as it were, blind ends. Now in the mammalian brain the reticular ganglion lies scattered among fibres which come from the higher centres, and the interpellation might be made whether, after all, the reticular ganglion be not a mere intercalar station for fibres derived from a higher source. Originally the ganglion was an independent station. In reptiles this body of cells is too considerable to account for a termination in them of the few cerebral fibres possessed by these animals. And, on the other hand, the vertical strands are notably increased in their passage through the field of the medulla oblongata. The medulla oblongata with its reticular ganglion seems to be the great rhythmic centre. In fish the movements of the operculum and mouth, in sharks those of the spiraculum, in perenni-branchiate amphibians the branchial tree, in the infant the suctorial muscles, in all vertebrates the movements of deglutition, of the heart and respiratory muscles, all movements presenting a more or less regular rhythm, are under the control of the medulla oblongata. The early differentiation of this part of the cerebro-spinal axis is related to the manifestations of rhythmic movements in the embryo and their predominant importance in lower animals. The possibility should not be excluded that a rhythmic movement may be spinal, nay even controlled by peripheral ganglia (heart of embryo). A higher development, however, implies the concentration of rhythmic innervations at some point where that anatomical association may be effected which is the expression of the mutual influence these movements exercise among themselves. Two sets of phenomena must be borne in mind in studying the physiological pathology of the epileptic attack. First, the condition of the epileptic in the interval. Second, the explosion itself. Too much attention is paid to the last, too little attention to the first. The constitutional epileptic is characterised by a general deficiency of tone associated with exaggerated reaction and irritability. Thus the pupils are at once widely dilated and unusually mobile. The muscular system, though generally relaxed, manifests exaggerated reflex excitability. The mental state is characterised at once by great indifference and undue irascibility. In the same way the vascular system is depressed in tone in the interval with rapid marked changes under excitation. The state of the nervous system as a whole Spitzka forcibly compares to that of an elastic band which, being on the stretch continually, is apt to rebound violently when one end is let go. Under normal circumstances the band is less stretched and hence not as liable to fly so far when the check is removed.