REGENERATION IN A TROPICAL EARTHWORM. 359 



specimens mentioned at the outset of this paper. Such abnormali- 

 ties at least in the species under discussion appear to be adequately 

 accounted for as the products of hypo- or hyper-meric regenera- 

 tion. 



VARIA. 



Additional extensive experiments were begun to obtain informa- 

 tion as to the posterior limit of anterior regeneration by tail por- 

 tions, the anterior limit of posterior regeneration by head portions, 

 the regeneration of pieces with two-cut ends from various regions 

 of the body, etc. These experiments failed completely, as far as 

 the objects in view were concerned, because of a constant series 

 of accidents which will be described under the title of autotomy. 

 A few notes from the records of these experiments are given 

 herewith to indicate more clearly the unusual regenerative charac- 

 teristics of this worm. 



A. A short piece of eight segments from the middle portion 

 of worm 109 was still living on the eighth day after the operation 

 and responded quickly to various sorts of stimuli. Both ends had 

 healed over without any signs of regeneration. 



B. The forty-one anterior segments of worm no regenerated 

 in nine days new tissue five and one half millimeters in length. 1 

 and fixing. 



The new tail was composed of a long, metamerically differentiated 

 portion containing more than thirty segments, the anal segment, 

 and between these two a short region of formation of new meta- 

 meres. 



C. The anterior end of worm 132, a piece fifteen millimeters 

 in length, composed of twenty-four segments regenerated in two 

 weeks a tail fifteen millimeters long containing in the segmentally 

 differentiated region, fifty-four segments. 



D. A shorter anterior end from another worm regenerated at 

 its posterior cut surface a licad of several segments with a char- 

 acteristic mouth and prostomium. 



E. A twenty-three metamere fragment thirteen millimeters in 

 length from the posterior half of worm 118 in two weeks regen- 



1 The measurements noted were made on material that had been killed by 

 dropping into strong methylated spirits and then hardened in formalin. Old 

 and new tissue appeared to be uniformly contracted by this mode of killing 



