Using cell and tissue cultures, at least in basic studies, aims at a betterunderstanding of biochemical, physiological, and anatomical reactions ofselected cell material to specified factors under controlled conditions, withthe hope of gaining insight into the life of the intact plant also in its naturalenvironment. Compared to the use of intact plants, the main advantage ofthese systems is a rather easy control of chemical and physical environmentalfactors to be kept constant at reasonable costs. Here, the growth and developmentof various plant parts can be studied without the influence of remotematerial in the intact plant body. In most cases, however, the original histologyof the cultured material will undergo changes, and eventually may belost. In synthetic culture media available in many formulations nowadays, thereaction of a given cell material to selected factors or components can beinvestigated. As an example, cell and tissue cultures are used as model systemsto determine the influences of nutrients or plant hormones on developmentand metabolism related to tissue growth. These were among the aims ofthe “fathers” of tissue cultures in the first half of the 20th century. To whichextent, and under which conditions this was achieved will be dealt with laterin this book.