Studies on Regulation. IF. 



117 



November 8: 69 days after section: 



At this time the locomotion of the piece diverges only occasion- 

 ally and then slightly from a straight line, except sometimes after 

 strong stimulation when the piece turns to the left. The form is 

 still more nearly symmetrical (Fig. 20). The folds which were 

 visible at x in Figure 18 have disappeared in consequence of rear- 

 rangement or resorption of the superfluous parts (atrophy from 

 disuse?), though when the piece turns to the left after strong 

 stimulation folds appear temporarily In this region. 



The longitudinal boundary between new and old tissue is now 

 almost a straight line, i. e. the contraction of the cut surface which 

 occurred after removal of the right side is now scarcely percept- 



Fig. 22. 



Fig. 21 



Fig 23 



X-. 



Fig. 24 



Fig. 25. 



Fig. 26 



-■XX 



Fig. 27. 



ible. This change Is probably, like the contraction Itself, due 

 primarily to an alteration in mechanical condition, i. e. the changes 

 in mutual pressure and tension. 



II. August 31, 1902. The body was removed by a transverse 

 cut about I mm. posterior to the cephalic ganglia and the anterior 

 piece tlius obtained was split longitudinally (Fig. 21 ) . The lon- 

 gitudinal cut passed a little to the left of the median plane and so 

 through the left cephalic ganglion. In consequence of the con- 

 traction of the worm during the operation the course of the cut 



