with one mouth and a circle of tentacles, and two bodies and two feet, resulted. The bodies soon began to fuse together (Fig. 46, _E²_) into a single one, and when the fusion had extended to the region of the feet, they also fused into a single structure (Fig. 46, _E³_), so that a single hydra was produced. In another experiment, twenty-two posterior ends were united in the same way, and then one of the two components was cut in two. In five cases a single head developed on the aboral end of the smaller piece (Fig. 46, _D_). It is evident in this case that the union of the two pieces has been a factor in bringing about the development of an aboral head. Another of the grafts produced an aboral head, and also one in the region of union. The remaining sixteen grafts produced new heads, if they developed at all, only in the region of union. Peebles states that the regeneration of aboral heads takes place only when one component is cut off near the region of union of the two pieces. In general, it may be stated in regard to these experiments in hydra that when pieces are united in the same direction, that is, by unlike surfaces, a single individual is formed and no regeneration takes place where the union has been made, but when like surfaces are brought together, although perfect union may result, a process of regeneration takes place later, at or near the line of union. Even the presence of cut-surfaces at one or both cut-ends of the united components does not generally affect the result, although, in a few cases, it may change it, in so far that heteromorphic regeneration may take place from one piece. This sometimes leads to a suppression of regeneration at the line of union. The experiments do not show, perhaps, conclusively whether the heteromorphosis of the smaller component is due to the polarity of the larger component effecting a change in the smaller one, or whether the closing of the oral end of the smaller component (by its union with the other) brings about the result. All things considered, it seems to me that the larger component has directly influenced the other.