XV.—The Digestive Diverticula in the Lamellibranchs

Abstract

Because of the superficial resemblance of the digestive diverticula of the Lamellibranchs, and of many other Invertebrates, to the liver of the Vertebrates, and the discovery in them of glycogen by Bernard (1855), they became known as the “liver.” Weber (1880) later introduced the name hepatopancreas as a result of his discovery of the secretory powers of the diverticula in the Crustacea. In spite of the fact that none of the constituents of bile has ever been discovered in the Invertebrates, and that the digestive diverticula are in no way analogous to the liver of the Vertebrates, as Jordan (1912) has shown in his review of the subject, the terms “liver” and “hepatopancreas,” as well as the less questionable designation “digestive gland,” are still generally used. Moreover, no attempt is made to distinguish between these organs in the different groups of Invertebrates although both their structure and function in, for example, the Lamellibranchs, Gastropods, Cephalopods, and Crustacea are totally different. In some cases they constitute a digestive gland; in others, including the Lamellibranchs, as I hope to show in this paper, their function is that of assimilation, and so they are most suitably designated digestive diverticula.