174 ADA R. HALL 
motor movements were recovered. This required fourteen 
days. The worm which regenerated for eleven days shows a 
very curious manner of growth. <A strand of cicatrix cells has 
united the cut ends of the longitudinal muscles. This strand 
shows the first steps in the regeneration of that muscle layer. 
But further, these same cells have entirely filled the space up to 
the nerve cord, have become attached to its cut ends, and have 
drawn together across the three-metamere gap. Thus the nerve 
cord is united and lies on a definite strand of cicatrix tissue. The 
circular and part of the longitudinal muscles around the cut 
have been massed together between the strand and the epithe- 
lium. The digestive tract also is folded and the mesenteries of 
these three segments are pulled together so that they lie at an 
angle. This would seem to indicate that the first step in the 
regeneration process is the uniting of the cut ends by scar tissues. 
In the worm which regenerated for fourteen days this drawing 
together was not so pronounced, a longer stretch of strand lying 
between the cut ends of the cord. The mesenteries were washed 
away in staining the slide, so that proof of the length of the cord 
was lacking: However, there was some bunching of the muscle 
fibers between the cord and epithelium and the cord appeared 
shorter than normal. 
2. Present experiments. In my present work I have attempted 
to verify these results, and also have allowed worms to live for 
several months in dirt after recovery from such an operation, in 
order to see if complete regeneration of all parts takes place. 
Before placing them in the dirt the exact position of the cicatrix 
is established by counting the segments from head to cut. 
In these experiments worms were killed at different intervals 
to get an idea of the steps in the process. Recovery of the 
movements occurs in from eleven to fourteen days in most cases. 
One worm killed after fourteen days had not recovered, but 
shows some interesting facts. The whole ventral part of the 
worm for five segments was filled in with cicatrix cells (fig. 16). 
These show differentiation for the muscle layers, which is appar- 
ent in the orientation of the cell nuclei. A delicate epithelium 
covers the lower border. Contrary to expectation, however, 
