Abstract

THE pyloric gland has long been known to exist in ascidians and is recognized to be of general occurrence in the tunicates with the exception of the Larvacea, but its function has not been determined with certainty. The organ usually forms a system of branching and anastomosing tubules enveloping the rectum and part of the intestine, and opening into the gut between the stomach and the intestine by a single duct. Varicose swellings in the tubules are found in many genera. Chandelon1, Isert2, Sokólska3, and van Weel4, among others, believed the pyloric gland to be digestive in function, contributing enzymes to the intestinal contents. They based their conclusion on the presence, in the walls of the tubules, of vacuoles which discharge into the lumen of the tubules. Todaro5, Colton6 and Azéma7 were among those who regarded the pyloric gland as an excretory organ.

References

1. Chandelon, T., Bull. Acad. Belg., Cl. Sci., (2), 39 (1875).
2. Isert, A., Arch. Naturgesch., 69 (1) (Berlin, 1903).
3. Sokólska, J., quoted in Huus, J., "Tunicata", "Kükenthal and Krumbach Handbuch der Zoologie", 5 (1934).
4. van Weel, P. B., Pubb. Staz. zool. Napoli, 18 (1) (1940).
5. Todaro, F., Mem. Accad. Lincei, (5), 11 (1902).
6. Colton, H. S., Biol. Bull. Woods Hole, 19 (1910).
7. Azéma, M., Ann. Inst. Océanogr., 17 (1937–38).