Studies on Regulation. IV. 127 



tivity between new and old portions agrees well with the fact 

 already mentioned in the section on "Regulation, Nutrition and 

 Use of Parts," that in starving pieces the old part usually dies and 

 disintegrates before the new, which may live and remain appar- 

 ently healthy for several days after the loss of the old part. 



CIRCULAR LOCOMOTION AND REGENERATION AFTER 

 OBLIQUE SECTION. 



Another method employed for bringing about circular loco- 

 motion was that of making oblique cuts at various levels posterior 

 to the cephalic ganglia. The results obtained by this method are 

 in some respects less striking than those described in the preceding 

 section, but since the cephalic ganglia are not injured in any way 

 by this method, a possible objection to the preceding series is ren- 

 dered invalid. 



The change in direction of the longitudinal axis of the regen- 

 erating tissue arising from a posterior oblique cut surface has 

 been mentioned (see also Figures 5-7). In this case the direc- 

 tion of locomotion was not altered by the cut, and, as might be 

 expected, the axis of the new tissue soon became coincident with 

 that of the old. In the course of similar experiments I found, 

 however, that if the cut were very oblique the contraction of the 

 cut surface following the operation might bring about circular 

 locomotion. Figure 46 represents the manner in which such a 

 cut is made, and Figure 47 the piece after contraction. It Is 

 evident that contraction produces a marked curvature In the lon- 

 gitudinal axis, and therefore the piece In advancing turns con- 

 stantly toward the cut side. It was found necessary to make the 

 cut in the anterior region of the body in order that markedly 

 circular locomotion might occur, because if the cut were made 

 near the middle of the body or in the posterior half, the part 

 of the body in which the axis was not affected by the cut was so 

 long that the bilaterally symmetrical Impulse to movement from 

 this region nearly or quite counterbalanced the effect of the bent 

 portion, and the regenerating tissue grew out in the direction of 

 the old axis. In all cases where the circular locomotion was well 

 marked the cut was made either just anterior to the pharynx as 



