LOCALIZATION OF NEW AXES IN CORYMORPHA. 473 



was determined on the opposite side of the piece, that is, the dom- 

 inance of the new axis became effective through the stem at right 

 angles to the original polarity. Contact with the substratum may 

 have assisted in determining the lateral stem region as a basal end 

 (Child, '2/0, b, c), though this region was not found in contact 

 when the piece was observed, but if the new polarity were not con- 

 cerned in localizing the base it would probably have arisen at or 

 near the proximal end of the piece. At this stage then the piece 

 represents two distinct polarities at right angles to each other. In 

 later stages the form became bipolar-unipolar, the new base be- 

 coming the base for both hydranths and the stem region proximal 

 to the lateral polarity gradually undergoing resorption. 



Fig. 7 shows another case from the same series at a stage four 

 days after operation. Here also the first apical hydranth was 

 removed and the figure shows the second developing. Fig. 8 

 shows the same form three days later. Lateral stem regions are 

 developing into a new basal end in relation to each hydranth. In 

 this case as in the preceding, contact may perhaps have been con j 

 cerned in producing conditions favorable to base development from 

 the side of the piece, but the localization of the two bases in rela- 

 tion to the hydranths indicates that the more distal regions of each 

 axis were to some extent concerned in localizing the bases. In 

 this case also the region of the stem proximal to the lateral hy- 

 dranth was gradually resorbed and the form became biapical and 

 bibasal. The two individuals would probably have separated 

 completely like most other double forms if they had been kept 

 long enough. 



In both of these cases the proximal stem region apparently 

 cannot maintain itself in the presence of the new lateral polarity 

 and is resorbed. The new polarity obliterates the old, probably 

 because the new represents higher levels of metabolism and so is 

 able to grow at the expense of the older stem regions. Such 

 growth of new axes at the expense of old stem regions has been 

 observed frequently in other experiments (Child, '270). 



Figs. 9-13 show cases from another series in which the pieces 

 included the whole or almost the whole length of the naked region 

 of 50-60 mm. animals. The figures show stages five days after 

 section. In Figs. 9 and 10 the lateral axes have not developed 



