470 C. M. CHILD. 



collected, only a single case of more than one hydranth on one 

 stem has been observed. In this case the stem was single over most 

 of its length, but divided into two distally and each of these bore 

 a hydranth. The two hydranths were equal in size and it was not 

 possible to distinguish one as terminal, the other as lateral. An- 

 other individual collected possessed a lateral stem outgrowth some 

 ten mm. in length but without hydranth or base at its tip. A 

 third individual possessed two manubria. These are the only cases 

 of axial multiplication found thus far in the collected material. 

 Considering the high frequency of such multiplication under ex- 

 perimental conditions (Child, '27 a, b) it seems remarkable that 

 it does not occur more frequently in nature. 



A simple lateral cut with smooth edges, extending a third or 

 even half way through the stem closes within an hour or two under 

 normal conditions and no new apical end or other outgrowth re- 

 sults from it. An earlier experiment on pieces of the actinian, 

 Harenactis, suggested that a modification of the procedure em- 

 ployed in that case might determine a new polarity and symmetry 

 in lateral stem regions of Coryinorpha. In the case of Harenactis 

 it was found that when mesenteries and muscles were much in- 

 jured or in large part removed the shorter transverse pieces con- 

 tracted in such a way as to bring distal and proximal cut edges of 

 the body wall together and union took place between these edges 

 about the whole circumference, giving rise to ' rings ' (Child, '09^). 

 It was found further that in places where the union between the 

 cut edges was smooth and without much new tissue no out- 

 growths developed along the line of union, while in places where 

 more new tissue developed groups of tentacles appeared. This 

 result led to the further experiment of mutilating opposite regions 

 of the two cut edges by means of numerous small cuts close to- 

 gether and vertical to the edge. When these two mutilated re- 

 gions came together they could not unite smoothly and extensive 

 growth of new tissue took place before healing was complete. 

 From this new tissue there gradually developed in some cases a 

 new normal individual (Child, '10, Figs. 5, 6). The new apical 

 region appeared only after complete closure of the wound by new 

 tissue. This new tissue gradually bulged outward because of the 

 internal water pressure, continued to grow and finally developed 



