470 C. M. Child. 



But another important feature of the movements in the absence 

 of the cephahc gangha must be noted, viz: that different pieces 

 differ from each other in the degree of coordination, power, and 

 frequency of their movements. Pieces from vs^hich the anterior 

 end has been removed by a cut only a short distance posterior to 

 the cephaHc gangha are capable of a somev^^hat greater degree of 

 activity than those from which the anterior half or two-thirds of 

 the body has been removed. In general it appears that the greater 

 the remaining portion of the central nervous system the more 

 complete the activity. 



We may consider first the case of a specimen from which the 

 anterior end has been removed by a transverse cut two or three 

 millimeters posterior to the cephalic ganglia. Such a piece is 

 capable of locomotion but the advance is very slow and uniform. 

 In my account of the normal movements (Child, '04) I called 

 attention to the fact that locomotion in Leptoplana is accom- 

 plished both by means of cilia and by muscular contraction, parts 

 of the margin being extended and attached to the substratum and 

 then undergoing contraction, thus dragging the body forward. 

 The muscular factor is especially conspicuous after strong stimu- 

 lation. In the specimen deprived of the cephalic ganglia, how- 

 ever, progression is accomplished largely by means of cilia, hence 

 the slow, uniform, gliding character of the movement. The 

 specimen is apparently capable of performing all the muscular 

 movements necessary for muscular locomotion but they appear to 

 lack perfect coordination. Occasionally the piece seems to suc- 

 ceed in using its muscles in some degree effectually, but it is 

 probable that these instances are simply due to chance coincidence 

 of particular muscular contractions. As the piece is more and 

 more strongly stimulated the muscular contractions become more 

 and more violent, although not coordinated, until finally the whole 

 piece is involved in convulsive movements during which it may 

 roll up and unroll or twist and squirm about, often turning over 

 with ventral surface uppermost. 



Use of the posterior margins and posterior end of the body as 

 organs of attachment occurs to some extent in these pieces. As 

 the piece glides over the substratum parts of these regions can be 



