Jelly-Fish, Star-Fish, and Sea-Urchins: Being a Research on Primitive Nervous Systems

The work presents a detailed physiological and morphological study of jelly-like medusae and echinoderms, combining microscopic description with experimental intervention. It describes body structure, sensory organs, and nerve arrangements, then reports stimulation and sectioning experiments on both covered- and naked-eyed medusae to test conduction, coordination, and localized control. It analyzes spontaneous and induced rhythmic contractions, the effects of poisons, and mechanisms of co-ordination, comparing medusae responses with those of starfish and sea-urchins to illuminate primitive nervous systems. Methods and results are presented consecutively to show how simple neural organization supports reflexes, rhythm generation, and integrative behavior.