Notes on Echinoderm Morphology, No. VI. On the Anatomical Relations of the Vascular System

Abstract

ABSTRACT I drew attention in my last note1 to the striking variations in the results of observations upon the vascular system of the Echinoderms, which have been made by different Continental naturalists. The leading member of the French School, Professor E. Perrier, asserts positively that the so-called “heart “of the Echinozoa is an excretory gland, which communicates with the exterior through the madreporite, and is entirely free at its inner end, no vessel proceeding from it to join an oral ring; in fact, it is not a part of the blood-vascular system at all. Professor Perrier had arrived at this conclusion as the result of his own observations upon Urchins and Starfishes, together with those of Apostolidès upon the Ophiurids. He totally denies the existence of the radial blood-vessels described by Ludwig in the Asterids; and as regards the Urchins he, like Hoffmann, is able to find but one vascular ring around the mouth. This is described as connected with the water-tube (stone-canal) and the radial vessels supplying the tentacles, and also as the ring in which the ventral or internal marginal vessel of the intestine originates. “Il y a done bien réellement communication entre l’appareil vasculaire intestinal et le prétendu appareil aquifère.”2