(a) _The Polyp._--Budding from the ectoderm alone has been described by A. Lang [29] in _Hydra_ and other polyps. The tissues of the bud become differentiated into ectoderm and endoderm, and the endoderm of the bud becomes secondarily continuous with that of the parent, but no part of the parental endoderm contributes to the building up of the daughter-polyp. Lang regarded this method of budding as universal in polyps, a notion disproved by O. Seeliger [52] who went to the opposite extreme and regarded the type of budding described by Lang as non-existent. In view, however, both of the statements and figures of Lang and of the facts to be described presently for medusae (_Margellium_), it is at least theoretically possible that both germinal and vegetative budding may occur in polyps as well as in medusae. (b) _The Medusa._--The clearest instance of germinal budding is furnished by _Margellium (Rathkea) octopunctatum_, one of the _Margelidae_. The budding of this medusa has been worked out in detail by Chun (HYDROZOA, [1]), to whom the reader must be referred for the interesting laws of budding regulating the sequence and order of formation of the buds. The buds of _Margellium_ are produced on the manubrium in each of the four interradii, and they arise from the ectoderm, that is to say, the germinal epithelium, which later gives rise to the gonads. The buds do not appear simultaneously but successively on each of the four sides of the manubrium, thus: 1 3 4 2 and secondary buds may be produced on the medusa-buds before the latter are set free as medusae. Each bud arises as a thickening of the epithelium, which first forms two or three layers (fig. 47, A), and becomes separated into a superficial layer, future ectoderm, surrounding a central mass, future endoderm (fig. 47, B). The ectodermal epithelium on the distal side of the bud becomes thickened, grows inwards, and forms a typical entocodon (fig. 37, D, E, F). The remaining development of the bud is just as described above for the indirect method of medusa-budding (fig. 47, G, H). When the bud is nearly complete, the body-wall of the parent immediately below it becomes perforated, placing the coelenteric cavity of the parent in secondary communication with that of the bud (H), doubtless for the better nutrition of the latter. Especially noteworthy in the germinal budding of _Margellium_ is the formation of the entocodon, as in the vegetative budding of the indirect type.