_L_, A section through a lobe of the wattle of a hen. 1, The epithelial layer. 2, A dense vascular layer. 3, A vein. 4, An artery. 5, A loose fibrous vascular structure. ] The _gray matter in the cord_ is in the form of two commas placed with their backs together with the central canal passing between them. The central canal is located in the center of the cord. As the cord nears the medulla oblongata the form of the gray matter changes. The second, the third, and the fifth ganglion centers are arranged laterally, and show a distinct side-horn group. The central canal separates the two Clark’s columns; later the side-horn group enlarges and extends ventrally around the anterior horn group and joins on the other side in half-moon shaped formation. The _central ganglionic mass of the spinal cord_, the center for the enteric visceral system, is divided into three complex parts. First, there are cell groups on both sides of the posterior raphe. Second, the half-moon shaped ventral groups extending parallel peripherally described above. Third, lying between groups one and two a complex group, which possesses a large collection of cells. These furnish splanchnic nerve centers, the anterior supplying motor nerves and carrying motor impulses outward, and the superior sensory which carry impulses to the centers. The cell group of the superior horns takes a sidewise peripheral position (Gadow). The _cerebellum_ (Fig. 62, _C_, 2) is located above the medulla oblongata and posterior to the cerebrum. The cerebellum consists principally of a median lobe called the worm. The lateral lobes are conical and rudimentary. The under part of the worm forms the roof of the fourth ventricle. On the upper surface of the cerebellum are numerous transverse markings (in the hen 13 or 14) which divide the lobe into leaves. When the cerebellum is cut lengthwise there is observed on the sectioned surface the peculiar arrangement of the white and the gray matter, the arbor vitæ, mentioned above. There is a small cavity in the cerebellum which communicates with the fourth ventricle. The _cerebellar cortex_ shows four parts, namely: First, the central part composed of white medullated fibers, between which are arranged neuroglear cells. Second, a rather reddish layer of cells of different sizes. These cells are embedded in a fine ground substance and are about 0.003 mm. in diameter. Third, a plain layer of large pear-shaped ganglion cells, the cells of Purkinje. Fine branches extend outward from the apex of these cells. Fourth, an outer gray layer which consists of small multipolar nerve cells with some neuroglear cells. The color of these three layers, according to Gadow, depends upon the color of the plumage; that is, if the plumage is dark, this layer is dark; if light, the layers are light. The marked coloring is said to be most distinct in the second layer.