The Nerve-Net of the Actinozoa III. Polarity and After-discharge

摘要: 1. Polarity exists in Calliactis , particularly the tentacles. In these, there is a centripetal polarity of anatomical origin, but addition physiological running centrifugally. More stimuli are required to facilitate conducting path centrally from point on tentacle than reverse direction. may originate by development differential facilitation rates. 2. some individuals, kind after-discharge observed. A series one or more extra contractions follows primary response stimulus. Though these appear only after stimulus has been given they indirectly caused it. Their presence absence cannot be predicted and seems bear no relation strength They introduce an arbitrary element into otherwise singularly regular between response. 3. Several possible sources for phenomenon considered, including synaptic junctions units nerve net, difficulties accepting any them. 4. The net possesses many properties nervous systems highly organised animals. danger pointed out employing unique skeletal neuromuscular system Vertebrata as standard which arrangement other phyla compared.