to go so far requires such time, while to go further requires a much greater. The crude ideas of space at this time must involve areas in the cortex devoted to motion and to general sensation situated in the Rolandic region. Those devoted to visual impressions are largely situated in the occipital region, and those devoted to time may be located in the frontal lobes. Further analysis of the more elaborate sense of space possessed by adults, involving the play of equilibrium and the appreciation of movement and direction in foreign objects, shows that cortical areas situated in nearly every part of the hemispheres are subsidiary to it and connected by fibre tracts of different lengths and courses. It is evident, therefore, that the mal-connection of cortical centres is at the root of various tropho-neurotic, nervous, mental, moral and other perversions exhibited in degenerates. Deformity and deficiency of the corpus callosum in some degenerates is but an expression of general defect of associating tracts. Convolutional aberration in others is but an expression of imperfect development of end stations and fibre systems. All mental and moral disturbances are associated with perversions of the functions of the cerebral hemisphere, but the converse, that cerebral hemisphere lesions only are the essential accompaniments of mental symptoms evinced during life, is not true. Lesions of the pons, the crura, and thalami are accompanied by more or less complete obliteration of consciousness, blurring of the perception, confusion in the intellectual sphere, even where the lesion is not of such a character as to disturb the neighbouring ganglia by pressure. Two explanations are possible of this phenomenon. Either the vaso-motor centre for the cortical vessels is under the control of isthmus ganglia partially, and hence isthmus lesions by irritation or destruction of the centre excite or paralyse the vascular tubes of certain cortical districts, or pathologic interruption of the great nerve tracts involves functional disturbance of cortical end stations. The first explanation is applicable in cases where general and widespread disturbance, somnolence, excitement, or depression are found. The latter where the disturbance is partial in character. If all avenues of sensory perception be closed unconsciousness in the way of sleep speedily follows. Interruption of the perception tracts is followed by corresponding phenomena, though less extensive when occurring in the isthmus territory. That an irritative lesion in the line of the centripetal tracts can influence cortical life is shown by thalamus lesions in which hallucinations are sometimes present. Here the cause of the hallucinations is in the lower centre, but the entry of these into the intellectual sphere can take place only in the cortical termination of that tract, since at this point only through the connecting associating tracts can it become a part of the ego.