Regeneration . and determines the polari-zation of the other piece. King finds that when two posterior pieces are united by their oralends, regeneration of one or of two heads often takes place at theline of union (Fig. 47, B, B^, B% as Wetzel had found. If a darkgreen individual is united to a hght green one, it can be seen that inmany cases the new heads are formed by both components, as shownin Fig. 47, B^. Later one of the posterior ends is absorbed, andthe halves may then separate (Fig. 47, B^, B^). If a number ofpieces are united, as indicated in Fig. 47, E, a number of heads maybe forme
Regeneration . and determines the polari-zation of the other piece. King finds that when two posterior pieces are united by their oralends, regeneration of one or of two heads often takes place at theline of union (Fig. 47, B, B^, B% as Wetzel had found. If a darkgreen individual is united to a hght green one, it can be seen that inmany cases the new heads are formed by both components, as shownin Fig. 47, B^. Later one of the posterior ends is absorbed, andthe halves may then separate (Fig. 47, B^, B^). If a number ofpieces are united, as indicated in Fig. 47, E, a number of heads maybe formed, and one or more of these may have a double origin. No GRAFTING AND REGENERATION 163 evidences of separation of the pieces was observed in cases of thissort. In one experiment two posterior pieces were united by obliquesurfaces, as shown in Fig. 47, C, and one of the two was afterwardscut across, as indicated by the cross-line. The subsequent re-generation that took place is shown in Fig. 47, C^. A head, com-. FlG. 47. — After King. A. Hydra split in two, hanging vertically downwards. Later the halvescompletely separated. B. Two posterior ends united by oral surfaces. B^. Same; it regen-erated two heads, each composed of parts of both pieces. IP. Absorption of one piece lead-ing to a later separation of halves. C. Two posterior ends united by oblique surfaces. Laterone piece partially cut off, as indicated by line. C^. Later still, two heads developed, one atA^, the other at il/. D. Similar experiment in which only one head developed, at yl/. E. Fivepieces united as shown by arrows. Four heads regenerated, one being composed of parts oftwo pieces. posed of parts of both pieces, developed at the cut-surface M, andanother in the region N in Fig. 47, C, composed of material of onecomponent. In another case, shown in Fig. 47, D, a head devel-oped only at the cut-edge, but it was made up of material from bothcomponents. A series of grafting experiments of another sort has been m
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