. The biology of birds. Birds. 120 THE BIOLOGY OF BIRDS. "5CI4 —Nervous system of a pigeon. From a specimen, , cerebral hernispheres of the brain: , optic lobes thrust to the side ; CB., cerebellum; , spinal cord ; , spinal nerves; , sym- pathetic nervous sj'stem; , brachial plexus to wing; , rhomboidal sinus in the dilated spinal cord (); , lumbar or sacral plexus of nerves uniting to form the sciatic nerve (scN ) going down the leg. composed of both sensory and motor nerve-fibres, as in the case of the vagus which goes to heart, stomacli,
. The biology of birds. Birds. 120 THE BIOLOGY OF BIRDS. "5CI4 —Nervous system of a pigeon. From a specimen, , cerebral hernispheres of the brain: , optic lobes thrust to the side ; CB., cerebellum; , spinal cord ; , spinal nerves; , sym- pathetic nervous sj'stem; , brachial plexus to wing; , rhomboidal sinus in the dilated spinal cord (); , lumbar or sacral plexus of nerves uniting to form the sciatic nerve (scN ) going down the leg. composed of both sensory and motor nerve-fibres, as in the case of the vagus which goes to heart, stomacli, and many other parts, con- trolling these, but also re- ceiving tidings from them. The spinal nerves, as already indicated, are mixed nerves, with sensory and motor components. There is on each side of the backbone a chain of sympathetic ganglia. These give off fibres to the adjacent viscera and blood-vessels. They are connected to one another in a chain, which is anteriorly linked to the brain. Each is also con- nected by a fine nerve- thread with the ventral root of a spinal nerve. As to the brain itself, it is in great contrast to that of reptiles, for it fills a spacious cranial cavity. The cerebral hemispheres are large, but they are not convoluted as in most mammals. Their roof is rather thin and their main mass consists of large corpora striata which bulge into the ventricles. The cerebral hemispheres meet the cerebellum dorsally and throw the solid optic lobes to the sides. To begin. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Thomson, J. Arthur (John Arthur), 1861-1933. New York : Macmillan
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectbirds, bookyear1923
