. Comparative physiology. Physiology, Comparative; Physiology, Comparative. THE ANALYSIS OF BEHAVIOUR IN ANIMALS 157 less distinct commissural portions composed of internuncial axons and ganglionic regions in which the cell-bodies and cell- connections are located. In Vertebrates the commissural part (white matter) encloses the ganglionic (gray) matter in the greater part of the ; while among invertebrates the is built up of discrete ganglionic and commissural parts. A peculiarity of the Vertebrate Hes in the fact that all secreting cells and smooth muscle fibres are inner
. Comparative physiology. Physiology, Comparative; Physiology, Comparative. THE ANALYSIS OF BEHAVIOUR IN ANIMALS 157 less distinct commissural portions composed of internuncial axons and ganglionic regions in which the cell-bodies and cell- connections are located. In Vertebrates the commissural part (white matter) encloses the ganglionic (gray) matter in the greater part of the ; while among invertebrates the is built up of discrete ganglionic and commissural parts. A peculiarity of the Vertebrate Hes in the fact that all secreting cells and smooth muscle fibres are innervated by motor neurones whose cell-bodies are located in subsidiary (autonomic) ganglia receiving efferent impulses from the cord but not themselves the centre of reflex activity. They Cerebral qanqljon Preganglionic neurone. f?ccepfor Postgangllonrc neurone Fig. 39.—Diagram of pedal ganglion ot Razor-shell. are thus distributive centres for multiplying impulses to be relayed to a large number of similar effectors of which simul- taneous and identical action is required. According to experi- ments by Drew (1908) on the nervous system of the Razor- shell clam an analogous state of affairs is seen in the pedal ganglion of the Lamellibranch (Fig. 39). Drew's experiments indicate that the pedal ganglion of the Lamellibranch only serves as a distributive centre for impulses from the cerebro-pleural ganglia. But in the gasteropod Aplysia, the pedal ganglion is, according to Frohlich (1910), a reflex as well as a distributive centre. The cardiac ganghon of Limulus is a structure which has probably no close analogy in Vertebrates, unless to the. 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 Hogben, Lancelot Thomas, 1895-. New York, The Macmillan Company
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