This is a type of germ-layer formation never found in the Hydro medusae, though of universal occurrence in all groups of animals above the Coelentera.
In some cases, however, medusabuds are formed on the hydro rhiza, as in Hydrocorallines.
Delobranchia, Lankester (vel Hydro Pneustea, Pocock).
On fusion with alkalis it yields para-oxybenzoic acid, and nas cent hydrogen reduces it to hydro shikimic acid.
Further, two distinct types of otocyst can be recognized in the Hydro medusae; that of the Leptolinae, in which the entire organ is ectodermal, concrement-cells and all, and the organ is not a tentaculocyst; and that of the Trachylinae, in which the organ is a tentaculocyst, and the concrement-cells are endodermal, derived from the endoderm of the modified tentacle, while the rest of the organ is ectodermal.
Habit in Hydro medusae.
It is convenient to distinguish two types of polyp by the names hydro polyp and anthopolyp, characteristic of the Hydrozoa and From Gegenbaur's FIG.
By continuing the introduction of methyl groups we obtain three series of homologous hydro carbons given by the general formulae CnH2,i 4.2, CnH2n, and CnH2n 2, each member differing from the preceding one of the same series by CH 2.