Regeneration of an Annelid Worm. 



89 



59 (755) 



The influence of the central nervous system in regeneration of 



an annelid worm. 



By A. J. Goldfarb. 



[From the Biologic Laboratories of the College of the City of New York.] 



In a previous investigation, it was found that the Morgan and 

 Nussbaum methods of operating worms resulted in a large mor- 

 tality, excessive injury, retarded healing and little regeneration. 

 The same results were obtained with the marine annelid worm 

 Amphinoma pacifica. 



By the method used successfully with Lumbricus 90 Amphi- 

 nomas were operated in such a manner that the nerve cord was 

 completely removed from 2 to 6 or more segments next the ampu- 

 tated level and with little or no injury to adjoining tissues. Over 

 151 worms served as controls. 



Regeneration was limited to definite levels. Within these 

 regions the head or the tail was regenerated in most of the worms, 

 even though the nerve cord had been removed. On subsequent 

 examination of serial sections it was found that in one group of 

 worms, the nerve cord had regenerated from the broken end as 

 far as the amputated level. Some of these worms had begun to 

 proliferate new tissues, others showed no sign of proliferation. 

 In a second large group, the regenerated nerve cord of the new 

 head was continuous with the old nerve cord. 



In a third group, the old nerve cord had grown a few ganglia 

 towards the amputated level, the remaining segments were entirely 

 devoid of nerve cord. Nevertheless the head had been regenerated 

 with its typical supraesophageal ganglia or "brain," its commis- 

 sures and even ventral nerve ganglion which grew posteriorly 

 towards the old cord. This group demonstrated that Amphinoma 

 as well as Lumbricus, and other adult organisms could regenerate 

 the missing organ without the contact of or stimulation from the 

 central nervous system. 



