From the Zoological Laboratory, Columbia University. 



obsf:rvations and experiments on regener- 

 ation IN LUMBRICULUS^ 



BY 



S. MORGULIS 



Introduction 549 



Autotomy or reproduction 551 



Experiments 556 



A Smallest part capable of regeneration 556 



B Rate of posterior regeneration 557 



C Regeneration of regenerated parts 566 



D A case of heteromorphosis 570 



E Some comments on anterior regeneration 571 



Regeneration and adaptation 572 



Summary 573 



List of literature 574 



This paper is the outcome of some experiments carried out 

 mainly during the months of last autumn. The problem was sug- 

 gested to me by Prof. T. H. Morgan, under whose direction this 

 work has been done, and it gives me great pleasure to avail my- 

 self of this opportunity to express my sincerest gratitude to Prof. 

 T. H. Morgan for having awakened in me an active interest in 

 the subject, and also for his kindness in revising the manuscript. 



INTRODUCTION 



1 he worms, 4-5 cm. long, are made up of 100-180 or even more 

 segments, each bearing four pairs of setae. The first seven to eight 

 segments are readily distinguished from the rest of the body, 

 and to them is applied the name "head." A median dorsal blood 

 vessel gives off in each segment a pair of lateral branches, and 

 also a pair of blunt finger-like diverticula, called the " blood glands," 

 which are absent in the first nine or ten segments. 



' This is the species originally described by Leidy as Lumbriculus limosus, and kindly identified for 

 me by Dr. Percy Moore, as Thinodrilus limosus. 



The Journal of Experimental Zoology, vol. iv, no. 4. 



