REGENERATION IN URONYCHIA 



107 



B. In the mid-phase of division. At this period the macro- 

 nucleus is fully condensed and ready for division, while the micro- 

 nucleus may or may not be divided. 



In experiments 66 and 72, the cells were cut longitudinally. 

 In no. 66 after 6 hours, A had started to regenerate while B had 

 divided into B' and B." All were then killed and B' found 

 to have a micronucleus; B" was a mere fragment with disinte- 

 grated macronucleus; A had long membranelles and new cirri, 

 but no micronucleus at all (see fig. 12). In no. 72 the cell was 



Fig. 12 Cell at the mid-phase of division cut longitudinally. A developed into 

 a single indi\idual with perfect motile apparatus but without a micronucleus 

 (A on right). B divided, forming B' and B" (on right). 



cut as shown in fig. 13. After 6 hours A was slowly regenerating, 

 B had divided into B' very small, and 5" normal. After 24 

 hours A and B" were perfect but B' had not regenerated. Lost 

 by accident. 



In experiments 2, 7, 22, 58, 63, 67, 68, 69 and 70, the cells were 

 cut transversely. In nos. 22, 58 and 67, the plane of the cut 

 coincided with the plane of division and in each of these cases 

 only two cells were formed, each perfect. In Experiments 2, 7, 

 63, 68 and 69, the plane of the cut was either anterior or posterior 

 to the plane of division and the larger fragment divided in the 



