GERM CELLS OF COELENTERATES 625 



plasm and the growing cell may be more or less filled with these 

 disintegrating nuclei and nucleoli (fig. 53). Muller ('08) has 

 described this in Hybocodon and it was recognized by Kleinen- 

 berg ('72) in hydra and by all who have since worked on hydra; 

 Wager ('09) has made a careful study of these nuclei, or 'pseudo- 

 cells/ in hydra. Many other authors have described such con- 

 ditions as found in various hydroids. 



In an egg in which the feeding is still progressing and whose 

 pseudopodia are still extended (fig. 53) the cytoplasm has become 

 filled with vacuoles and presents a distinctly alveolar appear- 

 ance. The dissolving nuclei of the absorbed oocytes usually 

 lie within some of the vacuoles and bodies of a different sort 

 occupy other vacuoles. In the particular egg figured the germi- 

 nal vesicle was without a nucleolus, though usually at this 

 stage of growth a nucleolus is present. The nuclear reticulum 

 is somewhat coarser than formerly but stains no more deeply 

 indeed at this time it shows a tendency to select a cytoplasmic 

 rather than a nuclear dye. In place of a nucleolus the egg 

 described had eight to ten small deeply staining bodies which 

 may be fragments of the nucleolus, or perhaps chromatin bodies. 



The extent to which a growing egg forms pseudopodia is well 

 shown in figure 55. This is a reconstruction of the stomach and 

 growing eggs of one individual studied. There were a great 

 many small oocytes present all about these eggs, filling the 

 spaces and making up the rounded gonad; these have been 

 omitted from the reconstruction. There were two, perhaps 

 three, large growing eggs in this gonad, it is uncertain whether 

 the lower mass on the right of the figure is a distinct and inde- 

 pendent egg or a portion of the one above it. The egg on the 

 left of the stomach has abundant and uniformly distributed 

 pseudopodia, the large one on the right has but few outgrowths; 

 probably both eggs are approaching maturity. 



When the egg has reached its full growth the pseudopodia 

 are withdrawn, the cytoplasm rounds out and a globular ovum 

 is produced. The germinal vesicle and a portion of the cyto- 

 plasm of such an egg is shown in figure 54. The cytoplasm is 

 much vacuolated, no sign of the absorbed oocytes remains, but 



