This chapter considers cytological aspects of vegetative cells as well as the structure and coordinated activities of tissues. A coralline vegetative cell, such as one from perithallial tissue, consists of a lumen bracketed at each end by primary pit-connections and surrounded by a three-layered cell wall in which calcite is deposited. Under particular conditions calcified cell walls may lose their mineral impregnation, a process that is poorly understood. Possibly, growth at crust margins and branch apices includes decalcification of certain cells when secondary tissues are generated from preexisting calcified tissues. Three types of cellular connections occur in vegetative tissues of coralline algae, namely, primary pit-connections, direct secondary pit-connections and fusions between laterally contiguous cells. The tendency for cells in coralline vegetative tissue to unite by large canals has been shown by many anatomists. The biology of cellular fusions and the concommitant nuclear fusions needs to be examined using modern techniques.