REPRODUCTION 



223 



withdrawn in like manner and replaced by new ones. In some, at 

 least, according to the observation of MacDougall on Chi lotion 

 uncinatus (1925) such substitution does take place and it is quite 

 probable that it is universal. The interesting experiments of 

 Dembowska (1925) show that removal of a single cirrus of Stylo- 



Fig. 113.— Uronychia Iransfuga, merotomy and regeneration. 1, cell immediately 

 after division, cut as indicated; 2, fragment A of 1, three days after the operation; 

 no regeneration; 3, cell cut five hours after division; 4, fragment A of 3, three days 

 after operation, no regeneration; 5. cell cut at beginning of division as indicated into 

 fragments A, B, and C; A', B' , C", fragments A, B and C, twenty-four hours after 

 the operation; fragment A regenerated into a normal but amicronucleate individual 

 (A'); B, C divided in the original division plane forming a normal individual (<'') and 

 a minute but normal individual (B'). (After Calkins.) 



nychia mytilus causes regeneration of the entire motile apparatus, 

 but no such result follows extirpation of any body region that is 

 free from cirri or cilia. 



The phenomenon is obviously analogous to the absorption and 

 renewal of flagella in the flagellates. Whether or not there is a 



