To establish the exact relationship it is necessary not only to breed but to rear the medusa, which cannot always be done in 1 In some cases hydroids have been reared in aquaria from ova of medusae, but these hydroids have not yet been found in the sea (Browne [Io a]).
Many Gastropoda deposit their eggs, after fertilization, enclosed in capsules; others, as Paludina, are viviparous; others, again, as the Zygobranchia, agree with the Lamellibranch Conchifera (the bivalves) in having simple exits for the ova without glandular walls, and therefore discharge their eggs unenclosed in capsules freely into the sea-water; such unencapsuled eggs are merely enclosed each in its own delicate chorion.
The developing ova are 19.
To get at the female and the ova prolonged soaking in soap and water is necessary, the epiderm being rubbed away and the ointment then applied.
The fundamental uniform fact in nature is constant change (lravra Xwpei Kai ovSiv Ova); everything both is and is not at the same time.
