No. 6.] DEVELOPMENT OF PARYPHA CROCK A. 301 



form, the protoplasm near the periphery becomes more dense, 

 and the absorbed nuclei are found in various stages of disinte- 

 gration. The egg now lies on the outside of the mass of ger- 

 minal tissue and next to the wall of the bell. No evidence of 

 fusion with the primitive eggs was observed after this stage 

 was reached, although the two were still in contact. It is 

 quite evident, however, that the remaining germ cells grow 

 and unite to form new eggs later in the history of the parent, 

 since primitive eggs are often found in advanced stages of 

 growth, while two or three nearly mature embryos still occupy 

 the gonophore. In other cases the gonophores contained sev- 

 eral embryos in various stages of development, but no prim- 

 itive ova. Doflein ('96), p. 67, states that, although he was 

 unable to obtain sections to illustrate adequately the point, he 

 believes that the germ cells of Tubularia do unite to form new 

 eggs after the larvae have left the gonophore. In Parypha 

 there is no chance to doubt that new ova are formed even 

 before the exit of the larvae. 



Fertilization. 



As is the case in many of the hydroids, the process of ferti- 

 lization is shrouded in mystery. The fact that the eggs are 

 developed in closed gonophores makes it difficult to decide just 

 when fertilization takes place. In discussing the development 

 of Allopora, Hickson states that he believes that fertilization 

 occurs while the nucleus lies at the periphery of the egg, and 

 previous to the time when it becomes irregular in outline. 

 From the positions of the eggs in which these irregular nuclei 

 were found, i.e., next the manubrium, this might be the case 

 here, but nothing was discovered which threw any light directly 

 upon the matter. 



History of the Pseudo-Cells. 



The nuclei of the absorbed cells are found in various stages 

 of disintegration within the ovum. Some of them resemble so 

 closely the nuclei of the germ-tissue cells that, were it not for 

 the position and the vacuoles within which they lie, it would be 



