The connective tissue of the membranes and the body wall of Arion rufus (L.) shows the following details: 1. The vesicular cells (Blasenzellen) are characterized by numerous vesicles produced by the cell membrane. They appear in two different functional states: a) as cells, which contain a high amount of glycogen but only few membranes of the smooth-surfaced endoplasmic reticulum and b) as cells, which contain little or no glycogen at all but a good developed smooth-surfaced endoplasmic reticulum. 2. Ramified fibrocytes show numerous invaginations of the plasmalemma. The material closing the cell from outside, is found inside the invaginations. At a distance from the cell surface there are typical parallel collagen fibres. 3. The granules of the granulated cells (Körnchenzellen) are surrounded by membranes and show a concentrical layering. 4. The branching melanocytes contain pigment granules which also are enclosed in membranes and which are not of homogenous structure. In a matrix of lower density there lies the dense core with its irregular pale central part. © 1969 Springer-Verlag.
