Regeneration in Lumhricidus 569 



The parts of the third level regenerated from October 17 to 

 October 31 the tails A at an average of 4.4 new segments for each 

 old segment; and those of the fifth level regenerated in the same 

 time the B tails at an average of 2.6 new segments. During the 

 next two weeks, from October 31 until November 14 they had 

 regenerated at an average 2.4 segments and 1.7 segments, respect- 

 ively. The ratio between these rates of posterior regeneration is: 



4.4 , 2.4 



^~= 1.7, and ^^ = 1.4 

 2.6 '' 1.7 



The ratio between the rates of posterior regeneration of the little 

 worms formed from A and B is: 



o. II 



0.06 



The eighteen A^ and Bi tails, which survived and had regen- 

 erated heads were also cut in two. This operation was performed 

 on November 28, or two weeks after they had been separated from 

 the old tissue. 



At the end of two weeks again (December 12), only seven ante- 

 rior pieces from Ai were alive. The fate of these seven pieces is 

 shown in the following Table. 



This table shows that only the anus was formed, but no new 

 segments were produced in these seven worms. 



Other experiments gave similar results and need not be recorded 

 here. It is evident that a regenerated tail is not only capable of 

 regenerating a head, from its anterior cut surface, but also of 



