NewThoughtLibrary.com / DivineLibrary.org

the medulla, replacing, as it would seem, those that terminated there. From the pons Yarolii, where we come next, the white fibres advance in various directions, intersecting with transverse fibres connecting the two halves of the cerebellum, and passing upwards towards the cerebrum proper. The fibres thus going upwards constitute the crura, peduncles or stems of the cerebrum, and seem destined to terminate in the grey matter of the convoluted surface of the hemispheres. But in passing through the ganglia of the brain the thalami optici, and corpora striata the arrangement described above is repeated; that is to say, while part of the fibres proceed through the ganglionic masses, the rest stop short in the grey substance of those masses, which grey substance gives origin to other fibres to pass out with those that had an uninterrupted course through the bodies alluded to. Both sets together those passing through and those originating in the grey substance of the corpora striata, or thalami optici, constitute a portion of the white or fibrous substances of the hemispheres, spreading out and terminating in the grey matter, or cortical layer of the convolutions. They are the first of three classes of fibres, described above, as constituting the white matter of the cerebrum, that is to say, the ascending or diverging class.

Whatever number of central masses we may calculate as interposed between the spinal cord beneath, and the convoluted surface of the cerebrum, the manner of communication between them is found to be as now stated. The fibres passing between one intermediate mass and another, are partly transmitted and partly arrested. "Wherever grey matter exists, there is the commencement or termination of white matter. The fibres that enter the cerebellum from the medulla oblongata terminate in whole or in part in its outer layer of grey substance, and in that substance a new set of fibres originate to pass to other parts of the brain,