Studies on Regulation. 487 



the pieces of Series 73 (Figs. 9 and 10) and those of Series 81 

 (Figs. 26 and 27) as between Series 82 (Fig. 11) and Series 80 

 (Figs. 24 and 25) in regard to the functional activity of the new 

 tissue. The greater activity of the smaller pieces without gan- 

 glia is, to a certain extent, counterbalanced by their more imper- 

 fect coordination. Numerous comparative observations were 

 made upon the pieces of the three series in order to determine if 

 possible whether actual differences in motor activity did occur, 

 and I concluded that in the pieces of Series 73 (Figs. 9 and 10) 

 the new parts were somewhat more active than in the other two 

 series, though the coordination of movements appeared to be 

 more imperfect. Thus it is evident that these pieces considered 

 by themselves afford few data of importance for or against the 

 present view, since the differences in activity are at best slight. 

 But the fact that the difference in the amount of regeneration at 

 different levels is much less marked in pieces without ganglia than 

 in those with ganglia is what might be expected according to the 

 views above expressed, since the differences in motor activity in 

 the different cases are certainly much less in the former than in the 

 latter series. 



The consideration of the third question is next in order, viz: 

 why the difference in the amount of regeneration between pieces 

 with and those without ganglia appears chiefly during the later 

 stages of regeneration and only to a slight extent or not at all 

 during the earlier stages. Comparison of Figs. 8, 13 and 20 

 and 21 (pieces with ganglia) with Figs. 7, 14 and 22 and 23 

 (pieces without ganglia) shows that during the first two weeks 

 the amount of regeneration does not differ greatly in the two sets. 

 In most cases the amount of new tissue seems to be slightly greater 

 in the pieces with ganglia, but the difference is not very marked. 



It is not possible at present to reach definite conclusions, but 

 certain probable reasons for this condition suggest themselves. 

 In the first place it seems probable that the first outgrowth of new 

 tissue from a cut surface in cases of this kind is determined by 

 factors different from those which determine the later regeneration. 

 Indeed it is by no means certain as yet how far this apparent 

 formation of new tissue is due to actual proliferation and how far 



