STUDIES ON REGULATION. 



VI. THE RELATION BETWEEN THE CENTRAL NERV- 

 OUS SYSTEM AND REGULATION IN LEPTO- 

 PLANA: ANTERIOR AND LATERAL 

 REGENERATION. 



BY 



C. M. CHILD, 



University of Chicago. 



With 64 Figures. 

 A. ANTERIOR REGENERATION. 



Anterior regeneration in Leptoplana differs widely from pos- 

 terior regeneration (Child, '04b) as regards its apparent relation 

 to the central nervous system. In the absence of the cephalic 

 ganglia it is very incomplete both qualitatively and quantitatively: 

 regeneration of the "head" never occurs when the ganglia are 

 absent. 



The work of Schultz ('02) upon polyclads has afforded similar 

 results, but the interpretation given by Schultz differs widely 

 from that offered below. Schultz denies the existence of a rela- 

 tion of any kind between the central nervous system and anterior 

 regeneration and believes that the almost complete absence of 

 anterior regeneration from levels posterior to the ganglia is due 

 to the fact that the margins of the cut surface unite and so pre- 

 sent a mechanical obstacle to regeneration. As will appear 

 below this is certainly not the case in Leptoplana tremellaris and 

 probably not in L. atomata, the species employed by Schultz for 

 his experiments. Schultz's experiments were apparently con- 

 fined wholly to the region posterior to the ganglia, where a head 

 never regenerates: if he had extended his examination to the 

 region of the ganglia and that anterior to them there is little 

 doubt that he would have reached very different conclusions. 



The relation between the cephalic ganglia and motor activity 



