抄録
Many kinds of dendritic structures in nature, such as rivers, blood vessels, electric breakdown patterns, cracks, viscous fingers and aggregates of fine particles, are reviewed based upon their mathematical models, with an interest in a common origin of these structures. It is stressed that the role of their formation is played essentially by an ensemble of conservative flows, and that the ensemble forms a dendritic structure if the flows have a tendency to aggregete each other.
