40 



EDGAR DAVIDSON CONGDON. 



Since the egg is found in the entoderm of the hydranth and is 

 always in the ectoderm while in the pedicel, it is apparent that it 

 must pass through the mesogloea at the restricted neck which 

 joins the hydranth and pedicel or in the lower part of the 



FIG. 8. 



hydranth. It is probable that the passage is at the former place 

 because not only is the wall very thin there but the egg on its 

 arrival has often attained a diameter greater than the thickness of 



the wall. In a single preparation 

 an e SS was found in the ectoderm 

 at the end of the pedicel. The 

 mesogloea at its anterior end was 

 almost gone. 



On its arrival in the hydranth 

 the ovum is so large that it pushes 

 the surrounding entoderm far out 

 into the enteric cavity. The growth 

 of the gonophore by the outpush- 

 ing of the body layers, and the 

 formation of the spadix duplicate 

 the processes in E. ramosnnt' Since 

 that has been already outlined it is 

 not necessary to consider it here. 



Growtli of the Egg. The 

 smallest ova are dissimilar to the 



ectoderm cells in all details of structure. , The cytoplasm is 

 granular and deeply staining. It sometimes contains vacuoles 

 which are most common near the periphery. The nucleus has a 

 distinct membrane, a spherical nucleolus and a chromatin retic- 

 ulum (Fig. 9). 



FIG. 9. 



