. Comparative physiology of the brain and comparative psychology. Brain; Psychology, Comparative. EXPERIMENTS ON MEDUSA and more ganglion-cells, and is connected with the upper ring by nerve-fibres. In addition to this ring, which is called the central nervous system, there is also a peripheral nerv- ous system, a plexus, consisting of nerves and scattered ganglion cells, spread out over the whole subumbrella (b, Fig. i), between the epithelium and the muscle-layer. The convex surface of the umbrella consists of a non-contractile, gelat- inous mass, and no nervous elements are to be found in i
. Comparative physiology of the brain and comparative psychology. Brain; Psychology, Comparative. EXPERIMENTS ON MEDUSA and more ganglion-cells, and is connected with the upper ring by nerve-fibres. In addition to this ring, which is called the central nervous system, there is also a peripheral nerv- ous system, a plexus, consisting of nerves and scattered ganglion cells, spread out over the whole subumbrella (b, Fig. i), between the epithelium and the muscle-layer. The convex surface of the umbrella consists of a non-contractile, gelat- inous mass, and no nervous elements are to be found in it. Acalepha^ (Fig. 2) have no continuous nerve-ring, but a row of separate nerve-centres (S, Fig. 2) extends around the margin of the umbrella, lying in the ectoderm, which covers the basis of the marginal bodies (sense organs). The number of these centres corresponds, at least in Aurelia aurita, with the num- ber of sense organs. This nervous system contains no ganglion-cells, but processes called nerve-fibres go out from special epithelial cells. The muscle-layer of the umbrella also is said to contain a peripheral nervous plexus (i).. FIG. i. HYDROMEDUSA. (Gonionemus vertens.) umbrella; £, subumbrella with muscles; c, man- ubrium ; d, margin of the swimming-bell with 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 Loeb, Jacques, 1859-1924. New York, G. P. Putman's Sons; [etc. , etc. ]
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