A migrating cilio-spore breaks away from a parent colony, settles down upon a substrate, and gives rise to another colony according to a well-determined pattern. After forming a peduncle, the ciliospore divides, producing a terminal macrozooid of the 1st generation and a lateral branch zooid. The terminal macrozooid elaborates more axial stalk and then divides again. This time, however, the branch zooid occurs on the opposite side of the main axis. In this way the terminal macrozooid, always apical, extends the main axis for as many as 33 nodes. The 1st division of the branch zooid gives rise to an axial microzooid and a stem-cell. The stem-cell generates alternating microzooids of the branch strain whereas the axial microzooids on some of the branches represent the presumptive ciliospores. During the life of a colony 6 types of zooids may be formed, although not all of them are apt to be present at any one time. The structure and spatial distribution of the heteromorphic zooids are given in some detail.