REGENERATION OF POLYCLADS 



51 



the margin of the cut by the fourth day. The digestive tract 

 appeared in the new part by the thirteenth day, and at the end 

 of four weeks the original form was fairly well restored, provided 

 that the cut had been made at a level more than quarter of the 

 animal's length from its anterior end. If the cut were more an- 

 terior than this, the worm did not attain its normal shape even 

 at the end of six weeks, but remained as in figure 2. The process 

 of morphallaxis occurs only to a limited extent (cf. Child, '04). 



I 



3^ ^ 4 



Fig. 1 Showing the two areas in which disintegration of P. littoricola in 

 chloretone takes place, A and B. 



Fig. 2 Regeneration of L. saxicola at the end of six weeks when cut was 

 made just posterior to brain. New material below broken line. 



Fig. 3 Regeneration of headless lateral piece of P. littoricola after eleven 

 days, showing practically no regeneration along the anterior margin and an 

 accumulation of material at the site of the new tail to the right. 



Fig. 4 Regeneration after five weeks of small piece from left side of head of 

 P. littoricola containing the left half of the brain. Accumulation of material 

 to form tail is marked. 



Fig. 5 Regeneration of remainder of the worm shown in figure 4, possessmg 

 the right half of the brain. Insufficient material has been added to restore com- 

 pletely the original shape. 



