The present volume includes papers presented in the International Symposium on Adaptations to Terrestrial Environment, held in Halkidiki, Greece from September 26th to October 2nd, 1982, as well as some invited ones from well known scientists working in the same field. It seemed rather optimistic to deal just in the same volume with such a variety of organisms (micro organisms to higher plants) on the basis of the1r adaptive strategies for survival on land. It would appear as the entire ecology ought to be included. It was a challenge for us. We undertook this challenge hoping that the output would not be unsuccessful. The Editors allowed the authors of the accepted papers great leeway in terms of thoroughness of their contributions. The quality of the papers included is high while some of them had to be rewritten in order to include valuable comments developed during the Symposium discussions. We have tried to include many papers from Eastern Europe since generally, because of the language problem, they do not get widely known. The Editors wish to express their thankfulness to UNESCO for sponsoring the Symposium in the frame of Man and Biosphere Program; to all scientists who have contributed papers in this volume; and to Mrs. A. Karamanli-Vlahopoulou for her patient and skillful typing of part of the manuscript."