While thus on the one hand continuing the Medulla Spinalis, the Medulla Oblongata is seen on the other hand to be continuous with the Brain--its white columns passing upwards in the _crura cerebri_, its cavity repeated in the other ventricles. Above it lie the ganglionic masses, the _corpora quadrigemina_, _optic thalami_, and _corpora striata_. Crowning these are the big and little brains, Cerebrum and Cerebellum. Figs. 9 and 10 represent this relation of Medulla Spinalis, Medulla Oblongata, and Brain. Fig. 11 is a purely artificial diagram which will give the reader some idea of the disposition of the white and gray substances. [Illustration: Fig. 9.--_Human Brain in Profile._ 1, Cerebrum; 2, cerebellum; 3, pons varolii and medulla oblongata. ] [Illustration: Fig. 10.--_One half of the Brain in Profile, from the inside._ 1, Convolutions of the cerebrum; 2, corpus callosum or great commissure uniting the two hemispheres; 3, arbor vitæ or branching arrangement of gray and white matter in the cerebellum; 4, pons varolii and medulla. ] [Illustration: Fig. 11.--_Diagram of a vertical section of the Brain_ (after Dalton). 1, Olfactory ganglion; 2, cerebral hemisphere; 3, corpus striatum; 4, thalamus; 5, corpora quadrigemina; 6, cerebellum; 7, ganglion of the pons varolii; 8, olivary body. ] 7. In man the Cerebrum is to the Cerebellum as 9 to 1. In the lower vertebrates the preponderance is still greater. The cerebrum is in our artificial systems commonly divided into three lobes. The frontal lobe is that portion which lies in front of the deep fissure named after Rolando; between that fissure and the “internal perpendicular fissure” lies the parietal lobe; behind this we have the occipital lobe; and, below the fissure of Sylvius, the tempero-sphenoidal lobe. Each lobe is again subdivided according to its convolutions.