. The physiology of domestic animals ... Physiology, Comparative; Veterinary physiology. 804 PHYSIOLOGY OF THE DOMESTIC ANIMALS. elevations (gyri) and depressions (sulci), convolutions and Assures, form so as to give to the brain its characteristic appearance, the degree of external com- plexity differing in different classes of animals. In fact, the strongest point in favor of the high importance of the cerebrum, and especially its connection with the mental functions, is seen in the progressive complexity of its surface in passing from the lower to the higher animals. In lishes, amphibia
. The physiology of domestic animals ... Physiology, Comparative; Veterinary physiology. 804 PHYSIOLOGY OF THE DOMESTIC ANIMALS. elevations (gyri) and depressions (sulci), convolutions and Assures, form so as to give to the brain its characteristic appearance, the degree of external com- plexity differing in different classes of animals. In fact, the strongest point in favor of the high importance of the cerebrum, and especially its connection with the mental functions, is seen in the progressive complexity of its surface in passing from the lower to the higher animals. In lishes, amphibia, and reptiles the cerebral cortex is smooth, and but a faint trace of the formation of fissures is to be seen in birds. In the lowest mammals also the hemispheres are smooth, as in the marsupials, the lowest rodents, if not also in the lowest so-called quadrumana, as in the lemurs. But, ascending to the higher orders of mammals, the hemispheres be- come more and more sulcated on the surface, until the ridges or convolutions become more and more numerous and complex as we reach the highest mammals or the highest genera in the several orders. The cerebral convolutions may be said to be characteristic of the brains of mammals, and may be considered, firstly, in regard to their general plan, and, secondly, their relative complexity within that plan. The highest degree of complexity of the cerebral convolutions is seen in the brain of man, of which the most important are represented in the following diagrams (Figs. 347, 348, 349). Each cerebral hemisphere is subdivided on its external surface into five lobes—the frontal, parietal, occipital, temporo-sphenoidal, and island of Reil. In the (1) frontal lobe are found three convolutions—the superior, central. and inferior frontal convolutions. Behind these comes the ascending fronted, sepa- rated from them by the precentral fissure and bounded posteriorly by the fissure of Rolando, which forms the anterior boundary of (2) the parie
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