The biota of the earth is being altered at an unprecedented rate. We are witnessing wholesale exchanges of organisms among geographic areas that were once totally biologically isolated. We are seeing massive changes in landscape use that are creating even more abundant succes sional patches, reductions in population sizes, and in the worst cases, losses of species. There are many reasons for concern about these trends. One is that we unfortunately do not know in detail the conse quences of these massive alterations in terms of how the biosphere as a whole operates or even, for that matter,...

Water is essential for life and without water no life exists. The liquid sur- rounding of an aqueous solution is the conditio sine qua non for most of the physiological responses and as such, water is as decisive for the occurrence of a single enzymatic reaction as it is for the global zonation of world vegetation. It is no wonder that scientists since early times have made every effort to describe and understand the functional interrelationships between water and the phe- nomenon of life. During the past half of this century, these endeavours in the field of botany have been marked by steps...