74 THE VOYAGE OF H.M.S. CHALLENGER. 



All other specimens of Cryptohelia available for the examination of the soft structures 

 proved to be female only. The ampullae in Cryptohelia are occupied by thin walled sacs. 

 Those in connection with newly-formed cyclo-systems at the tips of the branches of the 

 ccenosteum are small, and contain only a few gonophores in early stages (PI. IX. G) ; but 

 those attached to older systems are often of enormous relative dimensions, and appear as 

 long reniform bodies (PL IX. G), which are almost as large as the masses of the cyclo- 

 systems themselves in volume, and contain gonophores in all stages from the very 

 earliest upwards, and one or two mature planulae. 



The early stages in the development of the ovum of Cryptohelia were examined 

 in the fresh condition of the soft parts, without decalcification or use of spirit, the 

 ampullae being broken open and the gonophores removed from the freshly-dredged coral. 



The earliest stage in the formation of a female gonophore observed is the massing 

 together of a small cmantity of the endoderm cells of one of the canals of the ccenosarc 

 which enter the gonophore sac (PI. XL fig. 3). In the next stage observed, a cup- 

 shaped spadix of endoderm cells is fully formed, the cup being attached to the cceno- 

 sarcal canals by a pedicle. In the hollow of the cup rests a fully-formed ovum, with a 

 well-defined germinal vesicle and spot, its main mass being composed of fine rounded 

 particles. Only a single ovum is developed in relation with each spadix. A thin 

 reflection of the ectodermal investment of the spadix covers the ovum within its cup 

 (PL XL fig. 4, E). 



The ova must be in some manner impregnated within the gonophore sac. As 

 development proceeds the ovum increases in size, and the germinal vesicle and spot 

 disappear, and the ovum appears entirely composed of thickly-set oily globules. At 

 the same time the margin of the cup of the spadix, which increases in dimensions in 

 accordance with the ovum, becomes divided into a series of small rounded lobes, 

 about twelve in number, which embrace the lower part of the ovum. The cells com- 

 posing the spadix and its lobes being coloured dark chocolate, the contained colourless 

 ovum contrasts strongly with its support in appearance in the fresh condition of the 

 structures. 



The ovum, as it enlarges, becomes gradually drawn out into an ovoid form (PL 

 IX. G). On further development the margin of the growing spadix becomes fringe- 

 like in appearance, the lobes composing it lengthening and becoming forked at their 

 extremities (PL IX. S P). The ovum in this stage is much dilated, and drawn out 

 into an elongate ovoid form. Its contents are nearly transparent and highly refractive, 

 but dotted all through their mass with sparsely-scattered oil-globules of various sizes 

 (PL IX. OV). The reflection of the ectoderm at this stage still covers the ovum 

 within its cup. A space is enclosed all round the gonophore by this ectodermal mem- 

 brane, between the margin of the spadix and the ovum. This is filled by a perfectly 

 transparent fluid. 



