348 ^^^ Philippine Journal of Science 1913 



however, differ from the typical endoderm of the gastric cavity 

 by having a greater staining capacity and containing much gran- 

 ular material. The mesogloea is thin, about 1 /u, in thickness 

 except at the inner edges of the spadix where it is thickened as 

 a reinforcement to the tube. The egg itself lies in a cavity lined 

 with mesogloea. It seems to be attached along the inner edge 

 of the spadix. The ovum is large, sometimes reaching a length 

 of 0,3 mm. and a breadth of 0.15 mm., its long axis being paral- 

 lel to the sides of the hydranth. The bulk of the egg is made up 

 of large polyhedral deutoplasmic granules which give the egg 

 a reticulated appearance. The nucleus is large, 26 fifi in dia- 

 meter, with a nucleolus 3.5 ixfx. in diameter. Scattered among 

 the deutoplasmic granules in the egg are many zooxanthellae. 

 They are especially numerous around the nucleus of the egg 

 and near the periphery, probably ingested by the egg with endo- 

 derm cells (Congdon '06). Of these zooxanthellae, especially 

 in the younger eggs, many are in stages of division (fig. 4) . 



Congdon ('06) says with regard to the question of the included 

 bodies found in hydroid eggs : 



There has been a diversity of view as to the fate of the nuclei of cells 

 absorbed by hydroid eggs as well as to the method of absorption. Ciami- 

 cian, '79, applied the term "Pseudozellen" to spherical bodies found in the 

 egg of Tubularia Tnesembryanthemum which he considered to be formed 

 after the nuclei of the absorbed cells had disappeared. Brauer, '91, pub- 

 lished the results of the study of the same species, in which he agreed with 

 the conclusion of Ciamician as to the origin of the pseudo-cells. Also, in 

 a contribution to the development of Hydra, he says that pseudo-cells are 

 formed in the cytoplasm and are not degenerating nuclei. 



The three papers already mentioned, by Doflein, Smallwood, and Allen 

 described the nuclei of absorbed cells as undergoing divisions and degener- 

 ative changes characteristic of pseudo-cells. That name is therefore ap- 

 plied to them. 



In this species, the history of the nuclei does not exactly correspond to 

 any that have been outlined above but finds its closest parallel in the per- 

 sisting of nuclei as pseudo-cells. 



Congdon himself ('06) finds the included bodies of the egg 

 of E. hargitti to be nuclei of included endoderm cells, but he 

 does not find them passing through the division stages described 

 by Smallwood ('99) and Doflein ('96) for Tubularia and Pen- 

 naria. In the egg cell of E. griffini there are to be found a 

 number of zooxanthellae, many of them in stages of division, 

 which in size, position, and appearance agree so closely with the 

 included nuclei as figured by Congdon ('06) that the question 

 arises whether Congdon and, perhaps, the other authors men- 

 tioned above have not mistaken included zooxanthellae for nuclei 

 of included endoderm cells. Since the absorption of endoderm 



