H. BINDING and J. REINERT In collaboration with the first authors of this volume This volume is devoted to the development of cell clones and plants from ma­ nipulated cells: isolated protoplasts, cell fusion bodies, and transformed cells. Isolated protoplasts represent cells which are liberated from their walls and separated from the differentiation pattern of the organism. Investigations on re­ generation from protoplasts provide a better understanding of the process and control of developmental pathways. Whereas protoplast isolation results in alteration of the state of differentiation of a cell, protoplast fusion is a means for the creation of cells with novel genetic constitution. Fascinating features are (1) to hybridize cells which-unlike gametes -did not derive from meiosis products, (2) to bring together foreign plastids and mitochondria and to investigate their parasexual reactions, and (3) to match ge­ netic traits which had been separated for long periods of evolution. Highly sophisticated techniques have already been elaborated for the transfer of genes by the use of isolated DNA and gene transfer systems. Highly promising results have already been obtained by the use of Ti plasmids of Agrobacterium, but direct DNA transformation is also proving to be useful. Most of the results in these areas are preliminary and/or limited to a few sys­ tem.lt is the aim of this volume to present the main features, but at the same time to draw attention to problems and perspectives of protoplast regeneration and so­ matic cell genetics in order to stimulate further investigations.