Studies on Regulation. 509 



and that particular functional capacities are primarily dependent 

 not upon a given part but upon the relations between that part 

 and others. 



In another paper further data will be given in the consideration 

 of the relation between the central nervous system and anterior 

 and lateral regeneration. 



Before concluding, the study by Schultz ('02) of regeneration in 

 Leptoplana atomata requires brief comment. Schultz being chiefly 

 concerned with the morphological and histological features of the 

 process made no comparative study of regeneration from diff^erent 

 regions. He states that posterior regeneration is complete, but 

 apparently has not examined pieces from the region anterior to the 

 ganglia; in all his specimens the cuts were made posterior to the 

 ganglia. Schultz is inclined to deny that the ganglia are connected 

 in any way with regeneration, but his experiments along this line 

 concern chiefly anterior regeneration and will be considered at 

 another time. Experiments on posterior regeneration from levels 

 posterior to the ganglia and in their absence were apparently not 

 made by him. So far as his experiments are adapted to the prob- 

 lem which I have considered it appears that L. atomata agrees 

 essentially in all respects with L. tremellaris. But since his work 

 has a purpose widely diff'erent from that of my own it afix)rds no 

 further data for present consideration. 



D. SUMMARY. 



1. Pieces of Leptoplana deprived of the cephalic ganglia react 

 to stimuli less strongly than normal animals and to some not 

 perceptibly. A considerable degree of motor activity may be 

 present, and progression is possible but all movements are indefin- 

 ite and to a large extent uncoordinated. The behavior of pieces 

 without ganglia diff'ers somewhat according to size (amount of 

 nervous tissue present) and the level of the section (qualitative 

 diflPerences in difi^erent regions of the cords). Pieces from the 

 region anterior to the ganglia show scarcely any motor activity 

 except ciliary movement and die within a few days. 



2. Removal of about half of the tissue of the cephalic ganglia 

 does not appreciably diminish motor activity or coordination, but 



