MORPHOLOGY AND PHYSIOLOGY OF GENUS URONYCHIA 377 



the other was operated on at a mid-division stage. In the for- 

 mer the cut was made in a longitudinal plane between the pos- 

 terior cirri and extended a little to the left. The pieces were 

 united by a strand of protoplasm and seemed to rotate on each 

 other, so that when reunited they had the appearance as shown 

 in figure 26. 



In an attempt to determine whether a cut in the region of 

 the micronucleus would produce abnormalities, sixteen cells 

 were operated on. Four of these were successful. Two were 

 cut in early division. One of these did not complete division, 

 but developed as has been described for individual no. 114. 



TABLE 10 

 Uronychia setigera. Abnormal regeneration due to incomplete cutting 



The other completed division, but the anterior cell soon died 

 and the posterior became abnormal, although it lived for four 

 days. In the case of a cell operated on in mid-division the 

 posterior cell was injured, and although the anterior cell was 

 normal, the cirri of the injured part developed to at least twice 

 their normal length. In the fourth case the individual had al- 

 most completed division when the anterior part was injured. 

 Division was soon finished, but the cirri of the injured cell were 

 long and very irregular. 



It is doubtful whether abnormalities resulting from incomplete 

 cuts near the center of the body can be accounted for on the 

 basis of an injury to the neuromotor system, even if we assume 



