REGENERATION IN A TROPICAL EARTHWORM 

 PERI ONYX EXCAVATUS E. PERR. 



G. E. GATES. 



In the course of a recent study of the Oligochceta of Rangoon 

 a number of earthworms were found with reproductive apertures 

 in normal arrangement and position on the segment but displaced 

 one to four metameres anterior to or one to three metameres pos- 

 terior to their usual position. The prostates and ovaries had the 

 same definite relations to the sexual orifices in such individuals as 

 in normal specimens and hence were anterior or posterior to their 

 ordinary position to an amount equivalent to the dislocation of the 

 reproductive pores. None of the various metameric and organ 

 anomalies that appear in nearly all of the species of Rangoon 

 earthworms were noticed in specimens of the type just mentioned. 



Morgan (1895) found similar anomalies in specimens of Allolo- 

 bophora foctida and suggested (p. 404) that " In those cases in 

 which openings of the vasa deferentia occur on a segment anterior 

 to the 1 5th metamere, 1 we may be dealing with a case of incom- 

 plete regeneration of the anterior metameres. ..." But further 

 on he says, " That all of the cases can be explained in this way is, 

 I think, highly improbable," and (p. 450) "regeneration of the 

 anterior end will not account for any of those cases where the 

 vasa deferentia open on a matemere posterior to the fifteenth." 



No references to hypermeric regeneration of anterior ends in 

 earthworms could be found in the literature available. The ab- 

 normality (posterior dislocation) was found so frequently, how- 

 ever, that a series of operations was begun with the idea of learn- 

 ing whether or not such anomalous specimens would develop as 

 the result of regenerative processes experimentally induced in 

 earthworms of the species concerned. One of the animals first 

 used seemed to have such an unusual capacity for replacing lost 

 parts that an extensive series of experiments was initiated to dis- 

 cover the limits of this capacity. After several months it became 



1 In A. fcetida the normal position of the male pores is on segment fifteen. 



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