PHYSIOLOGY OF RECONSTITUTION OF PLANARIA LATA. 



129 



of cut surface in relation to size of piece. The deaths are practi- 

 cally limited to the first day or two following section. Pieces that 

 survive this period live, with rare exceptions, to the end of the 

 experiment and undergo some degree of reconstitution. In such 

 Very short pieces of P. dorotocephala the contraction of the cut 

 surface often brings about rupture elsewhere, and contraction at 

 this point produces further rupture in other regions and the piece 

 gradually breaks up. In P. lata also the contraction following 



Table I. 



Head Frequencies of Full-grown P. lata (11— 13 mm.) in Relation to 



Length of Piece and Level of Body. 



