Preface

Rhythmical behaviour is a quintessential pattern of life itself and is believed to play a key role in cell division and morphogenesis, to mediate all kind of movements, and to provide an advantageous strategy for evolution and adaptation of living organisms. Rhythms have fascinated people for more than 2000 years. As early as the fourth century B.C., Androsthenes, scribe to Alexander the Great, noted that the leaves of Tamarindus indica opened during the day and closed at night (Bretzl 1903). Some early writers notice single movements of parts of plants in a cursory manner, Albertus Magnus in the thirteenth century and Valerius Cordus in the sixteenth century, thought the daily periodical movements of the pinnate leaves of some Leguminosae worth recording. Ray in his “Historia Plantarum” at the end of the seventeenth century commences his general considerations on the nature of the plants with a succinct account of phytodinamical phenomena mixing up together the movements from irritability and the daily periodical movements; the latter, he says, occur not only in the leaves of Leguminosae, but in almost all similar pinnate leaves, and with these periodical movements of leaves, he places also the periodical opening and closing of the flower of Calendula, Convolvulus, Cichorium, and others.