. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. 268 ANATOMY OF VERTEBEATES observed to decussate, as in fig. 166, changing their relative within the slieath. The termination of efferent nerves on sentient surfaces of the skin appears to be plexiform : but they have been seen to enter the bases of the tactile papilla3 in the form of loops. The looped termi- nation has been distinctly seen by Henle upon the membrana nictitans of the frog, and by Valentin on parts of the formative matrix of teeth, fig. 167. 166 165 "Wavy course of nerve fibres, "n-ith
. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. 268 ANATOMY OF VERTEBEATES observed to decussate, as in fig. 166, changing their relative within the slieath. The termination of efferent nerves on sentient surfaces of the skin appears to be plexiform : but they have been seen to enter the bases of the tactile papilla3 in the form of loops. The looped termi- nation has been distinctly seen by Henle upon the membrana nictitans of the frog, and by Valentin on parts of the formative matrix of teeth, fig. 167. 166 165 "Wavy course of nerve fibres, "n-ithin the common slieath. 167 Diagram to show the derussntion of the primitive tibres within the tnmlv of a !Ri-\ e. t'Cy. ccvi. Amongst the nerve-fibres of the sympathetic system are some of a grey colour, sometimes called ' soft fibres,' vs'hich are flattened, homogeneous, more minute than the primitive fibres of the cerebro-spinal system, and characterised by small multinucleate bodies upon their sur- face, fig. 168. § 52. Mi/elencephalon of Fishes.—In the cold-blooded Vertebrates the pro- portion of the mass-form, or centres, to the thread-form, or conductors, of the nervous system is less than in the warm-blooded classes. In the Lancelet (^Branchiostoma), fig. 169, the neural axis, m d, shows no distinction between brain and myelon; it is a slender tract of nu- cleated cells, inclosed in a delicate pia mater, constituting a continuous chord, of opaline sub-transparency, ductile and elastic. It is depressed or band-lilcc along its middle third, which is slightly grooved along the medial line of the dorsal surface,. 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 Owen, Richard, 1804-1892; Cornell University. College of Veterinary Medicine. Flower-Sprecher Veterinary Library. fmo. London, Longmans, G
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