THE BIOLOGY OF BOTRYLLUS SCHLOSSERI: A REVIEW OF SABBADIN'S IDEAS AND STUDIES

More thean 50 years ago, Armando sabbadin introduced at the University of Padova (Italy), the colonial ascidian Botryllus schlosseri, setting up conditions for the permanent culture of this species. Attracted by its fascinating life cycle, he spent about five years in studying its biology, laying the foundations for future studies and producing a series of almost unknown papers, published in Italian, containing the evidences of many statements that are now an aquired background of researchers. These papers acount the value of the staging method introduced by Berrill in 1941 for B. schlosseri and then modified by Sabbadin in 1955, evidencing the relationship between bud growing and water temperature. Moreover, they state the regulative ability of colonies, able to survive in adverse environmental conditions and to rescue development when conditions improve. The papers present also different experiments of repeated bud extirpation, which allowed Sabbadin to evidence competition between right and left buds for both sexual and asexual reproduction. All these conclusions were based on data coming form daily observations of a number of treated and control colonies, and were expressed in form of tables and graphs which prove what we take now for assured. We review these unknown data, so that they become more visible to the scientific community and discuss recent publications which exploit some Sabbadin's assertions.