Budding as a rule does not result in the formation of independent organisms, but is rather comparable to the proliferation that has become the normal method of growth in sponges, except of course that individuality is much more marked in the component parts of a polyzoon colony than it is in a sponge. In the genera described in this volume budding takes place by the outgrowth of a part of the body-wall and the formation therein of a new polypide, but the order in which the buds appear and their arrangement in reference to the parent zooecium is different in the different groups. In the freshwater ctenostomes three buds are typically produced from each zooecium, one at the anterior end and one at either side, the two latter being exactly opposite one another. The parent zooecium in this formation arises from another zooecium situated immediately behind it, so that each zooecium, except at the extremities of the zoarium, is connected with four other zooecia, the five together forming a cross. The two lateral buds are, however, frequently suppressed, or only one of them is developed, and a linear series of zooecia with occasional lateral branches is formed instead of a series of crosses. In the phylactolæmata, on the other hand, the linear method of budding is the typical one, but granddaughter-buds are produced long before the daughter-buds are mature, so that the zooecia are frequently pressed together, and lateral buds are produced irregularly. In _Victorella_ additional adventitious buds are produced freely near the tip of the zooecium. Reproduction by spontaneous fission sometimes occurs, especially in the Lophopinæ, but the process differs from that which takes place when a _Hydra_ divides into two, for there is no division of individual zooecia or polypides but merely one of the whole zoarium. The production of reproductive bodies analogous to the gemmules of sponges appears to be confined in the polyzoa to the species that inhabit fresh or brackish water, nor does it occur in all of these. All the phylactolæmata produce, within their zooecia, the bodies known as statoblasts. These bodies consist essentially of masses of cells containing abundant food-material and enclosed in a capsule with thick horny walls. In many cases the capsule is surrounded by a "swim-ring" composed of a mass of horny-walled chambers filled with air, which renders the statoblast extremely light and enables it to float on the surface of the water; while in some genera the margin of the swim-ring bears peculiar hooked processes, the function of which is obscure. The whole structure first becomes visible as a mass of cells (the origin of all of which is not the same) formed in connection with the funiculus, and the statoblast may be regarded as an internal bud. Its origin and development in different genera has been studied by several authors, notably by Oka[AX] in _Pectinatella_, and by Braem[AY] in _Cristatella_.