THE REGENERATION OF A HETEROMORPHIC TAIL 

 IN ALLOLOBOPHORA FOETIDA. 



ABIGAIL CAMP DIMON. 



In a paper by Professor Morgan^ an account was given of an- 

 terior regeneration from three different levels in earthworms. 

 The results seemed to show that the internal factor determining 

 the formation of a heteromorphic tail might be the presence of 

 the stomach-intestine at the regenerating surface, and at Professor 

 Morgan's suggestion and under his direction, the following ex- 

 periments were undertaken. An attempt was made to test this 

 view by means of more exactly localized sections made near the 

 level of the beginning of the stomach-intestine. 



In Allolohophora foetida, the species used, the oesophagus ex- 

 tends to the fifteenth segment, the crop lies in the fifteenth and 

 sixteenth, the gizzard in the seventeenth and eighteenth, and at 

 the nineteenth begins the stomach-intestine, which extends pos- 

 terJorally through the rest of the worm. The external openings 

 of the vasa deferentia on the fifteenth segment served as con- 

 venient landmarks for determining the level of the section. The 

 worm was cut in two, the short anterior piece dropped into alcohol, 

 and its number of segments counted so that the exact level of the 

 cut could be recorded. The posterior piece was then left to re- 

 generate from forty-eight to one hundred and twenty days, when 

 it was killed, and sections made for study. In some cases a new 

 head, and other cases a new tail regenerated from the anterior end 

 of the posterior piece. In the regenerating head the new stomo- 

 daeum usually did not open into the old digestive tract, which 

 closed anteriorly, and no definite pharynx formed, A dorsal brain, 

 connected with the ventral nerve cord was usually present. Since 

 these conditions represented the most usual form of head regenera- 



lExperimental Studies of the Internal Factors of Regeneration in the Earth- 

 worm. Arch, fiir Entwickelungsmech. der Organ. Bd. XIV. pp. 562-591. 



