Beobachtung über einen merkwürdigen schöngefärbten Eingeweidewurm, Leucochloridium paradoxum Mihi, und dessen parasitischen Erzeugung in einer Landschnecke, Succinea amphibia Drap. Helix putris Linn.

Breslau und Bonn, Kaiserliche Leopoldinisch-Carolinische Akademie der Naturforscher, 1834. Large 4to (29.3 x 22.0 cm). 15 pp. [numbered 88-100, 100a-b]. One hand-coloured engraved plate. = First description of remarkable parasitic worm and its effects on an intermediate host, viz. snails of the genus Succinea. Carus was the first to discover this amazing life cycle, and describes and illustrates it into detail. "The worm in its larval, miracidia stage, travels into the digestive system of a snail to develop into the next stage, a sporocyst. The sporocyst grows into long tubes to form swollen "broodsacs" filled with dozens to hundreds of cercariae. These broodsacs invade the snail's tentacles (preferring the left, when available), causing a brilliant transformation of the tentacles into a swollen, pulsating, colorful display that mimics the appearance of a caterpillar or grub. . Infection of the tentacles of the eyes seems to inhibit the perception of light intensity. Whereas uninfected snails seek dark areas to prevent predation, infected snails have a deficit in light detection, and are more likely to become exposed to predators, such as birds. . Birds are the definitive hosts for this parasitic worm. The cercariae develop into adult distomes in the digestive system of the bird; these adult forms sexually reproduce and lay eggs, which are released from the host via the bird's excretory system. These droppings are then consumed by snails to complete the creature's life cycle. Overall the life cycle is similar to that of other species of the genus Leucochloridium. The resulting behavior of the flatworm is a case of aggressive mimicry, where the parasite vaguely resembles the food of the host; this gains the parasite entry into the host's body" (Wikipedia). Published in the Nova Acta Physico-Medica Academiae Caesareae Leopoldino Carolinae Naturae Curiosorum, volume 17. Includes a Spätere Zusatz (pp. 100a-b). Uncut. Paper a bit spotted, the plate browned, but the colouring good. Rare.