228 W. M. SMALLWOOD. 



Figs. 25, 26 ; and in late anaphase is very conspicuous, Fig. 27. 

 After the metaphase stage, the astral fibers are mostly composed 

 of granules, Figs. 25, 26. The interzonal fibers persist for some 

 time and are frequently bent as the cleaving cytoplasm passes 

 through them. At such times, the chromosomes lie at each end 

 of a V-shaped figure. As the fibers disappear and the chrom- 

 osomes become transformed into a nucleus, the centrosphere sub- 

 stance largely becomes an indistinguishable part of the cytoplasm, 

 but a small portion remains as a clear, narrow region surround- 

 ing the nucleus. This means that the deeply staining, newly 

 formed " resting nucleus" with a narrow transparent area around 

 it in cleavage is perfectly normal, being the last remains of the 

 centrosphere. 



PAPILL/E IN Hydractinia AND Pennaria, 



Hargitt (p. 469) has described these as ectosarcal phenomena. 

 My study confirms his and shows that in both of these hydroids 

 the papillae are common in the unsegmented egg and have even 

 been seen while the egg was in the medusa. There is no par- 

 ticular region on the egg where they arise. At first these 

 papillae were regarded as polar bodies, especially in Hydractinia, 

 but when they were found on the vegetal pole and the female 

 pro-nucleus was present at the animal pole in the same egg, such 

 an interpretation was impossible. I believe that these papillae are 

 what Miss Bunting saw and described as polar cells, which is a 

 mistake that might be easily made. In Pennaria these papillae 

 push the false membrane away from the egg as they form and 

 after being set free remain in this same structure for some time. 

 The papillae in both species are wholly devoid of chromatin and 

 so far as could be determined entirely cytoplasmic phenomena. 



FRAGMENTATION OF THE NUCLEUS, AMITOSIS. 

 Fragmentation. If by fragmentation of the nucleus is meant 

 that the entire nucleus disappears and its contents disperse 

 throughout the cytoplasm then I find no evidence of such a 

 process in these hydroids. But what shall be said of the chro- 

 matin changes before maturation in Hydractinia and in Pennaria 

 after maturation where large quantities of chromatin migrate into 



