92 ERNEST WARREN. 



Used or unfertilised, the ova of the germinal epithelium fuse, 

 in the majority of cases, into a single egg-mass (fig. 22) ; but 

 occasionally there are two such masses. In a densely gran- 

 ular mass, with nuclei in all stages of disintegration (fig. 25) , 

 I have been unable to distinguish with certainty the first 

 segmentation nucleus. The nearest approach is seen in 

 fig. 22, where the egg-mass contains about four nuclei, one of 

 which is shown in a state of division {dy.). Towards the 

 centre the egg-mass consists of vacuolated protoplasm, with a 

 number of large yolk masses and granules ; towards the 

 periphery the protoplasm is dense and finely granular and 

 there are no vacuoles. The nuclei are contained in this outer, 

 denser portion. On the formation of the egg-mass the 

 manubrium shrinks considerably (figs. 22-24). Fig. 26 is an 

 enlarged piece of an egg-mass, similar to that in fig. 22, and 

 containing some four or six nuclei. The nucleus (n.) is sur- 

 rounded by a clear area, and is characterised by staining 

 exceedingly faintly, owing to the small amount of chromatin 

 it contains. The nucleus consists of a delicate nuclear mem- 

 brane and a fine reticulum of chromatin. 



The egg-mass secretes a firm egg-membrane (fig. 26, e. di.). 

 In fig. 23 the embryo has developed further, and it is often 

 remarkably irregular in shape. At this period it consists of 

 some eighteen to twenty blastomeres, which are not separable 

 from one another by cell-outlines nor from the central 

 vacuolated mass containing innumerable granules and yolk- 

 masses. 



The matei^ial at my disposal has not permitted further 

 observations on the development of the actinula. 



In fig. 17 is represented a gonophore containing an actinula. 

 Such is shown in section in fig. 24. The remainder of the 

 yolk-spheres are contained in the endoderm. 'I'he number of 

 tentacles varies from about nine to twelve, although ten seems 

 to be the typical number. 



It is probable that these tentacles correspond to the basal 

 or proximal tentacles of the hydranth. The actinula in fig. 17 

 lias every appearance of being ready to emerge from the 



