514 C. M. Child. 



was described in a preceding paper (Child, '04a). It was found 

 that removal of more than half of the ganglionic tissue is followed 

 by a marked reduction in the power of coordination and motor 

 activity in general, though pieces without ganglia are capable of 

 slow progression and are able to right themselves when turned 

 over. A relation between the cephalic ganglia and the amount of 

 posterior regeneration was found to exist, but all the organs 

 removed are regenerated in the absence of the ganglia though in 

 smaller size or in some cases of less complexity than when the 

 ganglia are present. The various conditions to which the parts 

 are subjected in consequence of motor activity and other func- 

 tional activities are undoubtedly formative factors, as has been 

 demonstrated by experiment for certain cases (Child, '02, '03, 

 '04a), and since the motor activity is dependent in large degree 

 upon the presence of the cephalic ganglia the relation between 

 the ganglia and the amount of posterior regeneration is to be 

 regarded as indirect rather than direct, /. e., the ganglia them- 

 selves do not give rise to special formative stimuli but determine 

 and regulate the functional conditions and so exert an influence 

 upon regeneration. 



It now remains to consider whether the conditions of anterior 

 regeneration are similar to those of posterior regeneration or 

 whether additional factors are concerned. The diff"erences in 

 anterior regeneration from difi^erent levels in relation to motor 

 activity will serve as a basis for this consideration.^ 



The figures are drawn in the same manner and on the same 

 scale as in preceding papers. 



I. Anterior Regeneration from Levels Anterior to the Cephalic 



Ganglia. 



Removal of any part of the head anterior to the cephalic ganglia 

 is followed in all cases by rapid regeneration. It makes little 

 diff"erence whether a small part only or the whole region anterior 

 to the ganglia is removed. The larger the part removed the 

 longer the time required for complete regeneration, although 

 the rapidity of regeneration increases with the size of the part 



