c^6 S. Morgulis 



In the two cases, where the heads had regenerated, the size of 

 the worms did not differ sufficiently from other intact worms, and 

 there is no reason to suppose that these worms have necessarily 

 resulted from a spontaneous division somewhere about the middle 

 of the body. More likely the foremost few segments were lost by 

 a mere accident. 



Could any of the small pieces give rise to new worms and in 

 this way propagate the species .? I will show later that such pieces, 

 unless large, will soon die. Moreover if the worms always divided 

 in the middle of their body, we should expect to have as many 

 worms with regenerating heads as those with regenerating tails, 

 but this does not occur. A regenerated head has certain peculiar- 

 ities that distinguish it from a normal head, that can be detected 

 long after its completion. If it be true that the posterior pieces 

 generally perish what good would such a process of division be for 

 the continuation of the race. 



As to the evidence brought forward by v. Wagner, I can only 

 say that his statement is too uncertain, for, the presence of a large 

 number of smaller worms might be as much an indication of larval 

 development as of an asexual multiplication. 



EXPERIMENTS 



A Smallest Part Capable of Regeneration 



Bonnet found that when he had divided a worm into sixteen 

 pieces, each piece formed a perfect worm again. If we assume 

 120 segments as the average number for Lumbriculus, these 

 pieces would have contained seven to eight segments each. In 

 my own case a number of very small pieces one to five segments 

 each were first tried. 



In order to keep the smallest pieces alive, I first cut the worms^ 

 into large pieces and allowed the cut surfaces to heal over for eight- 

 een to twenty-four hours, and then cut off smaller parts near the 

 closed ends. By using this method I was enabled to keep alive 

 about one-third of the entire number of pieces for a time long 

 enough to give results. 



