ABSTRACT
The blue-green algae have traditionally been considered one of the groups of algae. However, since the advent of the use of the electron microscope in biology, they have been known to have a prokaryotic cell structure. Therefore, the blue-greens are now identified by other names, such as blue-green bacteria, however, cyanobacteria is the most common designation. Thus, the cyanobacteria are algae from an ecological perspective, but are bacteria and part of the Kingdom Monera from a cell-structure viewpoint. Their cell-wall structure clearly puts them in with the Gram-negative bacteria.
