Studies on Regulation. IV. 125 



nearly perpendicular to the posterior cut surface in this case than 

 in the two preceding cases, but this is to be expected from the 

 position of the latter. In this piece the regeneration of the left 

 cephalic ganglion was not delayed, the left margin of the head 

 became functionally active within a month after section (Fig. 

 42) and reduction of the curvature began and was completed 

 before death. 



4. A piece from the right side of the head: Figure 43, seven 

 days after section ; Figure 44, twenty days after section ; Figure 

 45, thirty days after section. The longitudinal cut in this case 

 injured the right ganglion to some extent. The piece became 

 greatly bent and simply revolved within a space little greater than 

 its own size. The posterior cut surface was brought into line 

 with the longitudinal surface. The posterior region grew out 

 toward the anterior tip of the head, but not at right angles to the 

 plane of the cut surface. Within the month the left cephalic 

 ganglion was partially regenerated and the left margin of the 

 head attained some degree of functional activity thus reducing 

 the curvature of locomotion and the axis of the body began to 

 straighten (Fig. 45). The piece did not, however, attain any- 

 thing like symmetrical form before death. 



A comparison of these four cases renders it sufficiently evident 

 that the angle between the plane of the posterior cut surface and 

 the regenerating body may vary greatly, while, on the other hand, 

 the relation between the direction of the outgrowth and the direc- 

 tion of locomotion is evident. 



In the cases described the relation between the functional ac- 

 tivity of the regenerating margin of the head and the direction of 

 locomotion has been pointed out. Attention has also been di- 

 rected to an apparent relation between the development of this 

 functional activity and the regeneration of the cephalic ganglion 

 of that side. The relation of the nervous system to regeneration 

 will be discussed elsewhere, but the fact may be noted here that 

 the presence or absence of the one ganglion appears to affect the 

 regeneration of the lateral margin of the head, but not that of 

 the posterior region. The latter may be formed in the usual man- 

 ner when only one ganglion is present, though it is usually not as 



