In one experiment two posterior pieces were united by oblique surfaces, as shown in Fig. 47, _C_, and one of the two was afterwards cut across, as indicated by the cross-line. The subsequent regeneration that took place is shown in Fig. 47, _C¹._ A head, composed of parts of both pieces, developed at the cut-surface _M_, and another in the region _N_ in Fig. 47, _C_, composed of material of one component. In another case, shown in Fig. 47, _D_, a head developed only at the cut-edge, but it was made up of material from both components. A series of grafting experiments of another sort has been made [Illustration: FIG. 48.--After Rand. _A._ Head of Hydra cut off. After eight days. _A¹._ Same after thirteen days. Three tentacles misplaced. _A²._ Same after eighteen days. _A³._ Same after twenty-one days. Misplaced tentacles absorbed. _B._ Anterior end of _Hydra fusca_, grafted upon side of body of another individual. Half an hour after operation. _B¹._ Same after four days. _B²._ Same after thirty-eight days. _B³._ Same, foot-region after forty-nine days. _B⁴._ Same after separating. Fifty-second day.] by Rand. A part of one hydra is grafted upon the side of another one in the following way. A groove is scratched in a film of soft paraffine covering the bottom of a dish filled with water. Another groove is made at right angles to the first one, and opening into it. A hydra (the stock) is placed in the first groove, and a wound made in its side with a knife. Another hydra is cut in two, and one piece (the graft) placed in the other groove, and its cut-surface brought into contact with the wound in the side of the first individual. If the operation is successful the exposed surfaces of the two hydras quickly unite, and the combination may be taken out of the groove. If the piece grafted on the stock included about the anterior half of a hydra, a two-headed animal results, as shown in Fig. 48, _B_. Although the graft has been united to the side of the stock, it soon assumes an apparently terminal position (Fig. 48, _B¹_). This is due to the graft sharing with the anterior end of the stock the common basal portion of the stock. A slow process of separation of the two anterior ends now begins, brought about by a deepening of the angle between the halves (Fig. 48, _B²_). This leads ultimately to a complete separation of the two individuals (Fig. 48, _B³_, _B⁴_). Each may get a part of the original foot, or a new foot may arise on the graft as the division approaches the base.