472 



C. M. CHILD. 



tion at the basal end is indicated by dotting. Fig. 5 is a case of 

 new lateral polarity in a piece some twenty-five mm. in length from 

 the middle of the naked region of a 70-80 mm. animal at a stage 

 four days after operation. The apical hydranth of the piece is 

 the second one developed, the first having been removed two days 

 after section. The apical and the lateral hydranth are so near to- 

 gether that they mutually inhibit tentacle development on the 

 sides facing each other and so have acquired a dorsoventrality 

 with respect to each other. The side of the stem opposite the 

 lateral hydranth shows an outgrowth which later becomes a base. 



FIGS. 5-8. Development of new axes from lateral regions of growth 

 determined by injury. Pieces 25 mm. in length from middle of naked 

 region of animals 70-80 mm. Figures are about twice natural size. Figs. 

 5 and 6, two stages of a piece developing a complete new axis at right 

 angles to the original polarity. Figs. 7 and 8, two stages of a piece which 

 develops a new basal end in relation to both lateral and apical hydranth. 



Fig. 6 represents the condition of the piece three days later. The 

 two hydranths have now developed separate stems and a new 

 base has arisen opposite the lateral hydranth. This development 

 of a new individual from the apical end basipetally following the 

 localization of the new apical end by the injury is an excellent ex- 

 ample of apicobasal dominance. The localization of an active 

 region by the injury determined a new hydranth, this determined 

 successive stem regions basipetally until finally a .new basal end 



