114 CM. Child. 



somewhat more slowly. Numerous experiments to be discussed 

 later have shown that with increasing injury to the cephalic gan- 

 glia the rapidity of movement and the degree of extension de- 

 crease, hence it is probable that the ganglion in the left piece has 

 suffered greater injury than that in the right. 



September 6 : 6 days after section : 



At this stage the regenerating posterior end has become distinct 

 and the first traces of the new pharynx are visible (Figs. 13 and 

 14). The posterior outgrowth is directed toward the cut side 

 and Its axis coincides with the curve of locomotion. The new 

 tissue is now functional to some extent, the tail being employed 

 by both pieces for attachment. 



September 20: 20 days after section: 



The two pieces are shown in Figures 15 and 16. The axis of 

 the new body is distinctly curved in both and the pharynx shows 

 in each case some degree of curvature. In each the part of the 

 ganglia removed is regenerating and In connection with It are a 

 few eye spots. The small new ganglion was distinctly visible in 

 the living specimens from the dorsal side. Both pieces continue 

 to move in circles, though with a somewhat larger radius than be- 

 fore, the change being due to the development and use of the new 

 tissue along the side of the head, which now evidently aids In loco- 

 motion and thus counterbalances in some degree the effect pro- 

 duced by the old parts. Portions of the margin of both the new 

 tissue and the old can be extended antero-laterally and attached 

 to the substratum, and tension Is exerted upon the other parts by 

 muscular contraction of these regions. But the power of the new 

 portions Is still much less than that of the old parts. Similarly, 

 in consequence of the curvature of the old parts, itself due to the 

 contraction following section, the effect of the cilia on these parts 

 is such as to cause movement in a curved line which Is not yet 

 counteracted by the cilia on the new parts. 



The larger right piece was accidentally Injured at this time and 

 its fupther history could not be observed. 

 October 12 : 42 days after section: 



Figure 17 represents the left piece at this stage. Considerable 

 reduction in size has occurred, but the amount of regenerated tis- 

 sue is relatively much greater than in Figure 16. The direction 



