The system of growing single cells and small cell aggregates in a liquid growth medium that is kept agitated by means of bubbling, shaking, or stirring so the cells do not settle out. Microorganisms and cells derived from callus tissues may be grown in this way. Growth is maintained by providing continuous aeration and by either transferring portions of the suspension to fresh medium or replacing a part of the culture with fresh medium. Suspension cultures of plant cells derived from friable masses of callus show a similar growth curve to cultures of microorganisms in that there is a lag phase and a logarithmic phase of growth. Cells of many plant species can be induced to form embryoids (see embryogeny
) in suspension culture, which, if removed from the culture and given appropriate conditions, will develop into complete plants.