As medusae are known to bud medusae from the radial canals there is nothing impossible in Aliman's theory, but it cannot be said to have; received satisfactory proof.
Whereas primitively any polyp in a colony may produce medusa-buds, in many hydroid colonies medusae are budded only by certain polyps termed blastostyles (fig.
A section apart, contrasting sharply with the families next to be mentioned, in none of which are free medusae liberated from the colony, so that only the characters of the trophosome need be considered.) 8.
Until quite recently the hydroids (Gymnoblastea) and the medusae (Anthomedusae) have been classified separately, since the connexion between them was insufficiently known.
And can only be explained on the theory that gonophores are degenerate medusae, and is inexplicable on the opposed view that: medusae are derived from gonophores secondarily set free.
The medusae In such a system the dactylo- 'gastropore, so that the entire single aperture subdivided by FIG.
Corymorphidae (including the medusa-family Hybocodonidae).--, Trophosome solitary polyps, with two whorls of tentacles; gonosome, free medusae or gonophores.
The gonosome consists of free medusae in Milleporidae, which are budded from the apex of a dactylozoid in Millepora murrayi, but in other species from the coenosarcal canals.
They show every transition between free medusae and sporosacs, as already described for hydroid colonies.
The sense-organs of medusae are of two classes: (1) pigment spots, sensitive to light, termed ocelli, which may become elaborated into eye-like structures with lens, retina and vitreous body; (2) organs of the sense of balance or orientation, commonly termed otocysts or statocysts.