Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0101clau Year: 1884 HYDEOZOA SIPHONOPIIORA. 247 they are, however, without nianubrium, mouth, tentacles, and sense organs. The deeply concave sub-umbrella surface of the nectocalyx is largely developed and has a very powerful muscular covering in rela- tion to its exclusively locomotive function. All the appendages are developed as buds formed of ectoderm, entoderm, and containing a central cavity which communi- cates with the central space of the stem. In the nectocalyces and gonophores an ecto- dermal ing
Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0101clau Year: 1884 HYDEOZOA SIPHONOPIIORA. 247 they are, however, without nianubrium, mouth, tentacles, and sense organs. The deeply concave sub-umbrella surface of the nectocalyx is largely developed and has a very powerful muscular covering in rela- tion to its exclusively locomotive function. All the appendages are developed as buds formed of ectoderm, entoderm, and containing a central cavity which communi- cates with the central space of the stem. In the nectocalyces and gonophores an ecto- dermal ingrowth gives rise to the covering of the sub-umbrella and to the generative product.* respectively (fig. 1ST). The ova, of which there is often only one in each female gono- phore, are large, and have no vitelline mem- after im- undergo a regular brane, and, pregnation, complete and segmentation. A nectocalyx (Diphyes) is the first structure formed in the free-swim- ming larva, or the upper part of the body of the larva gives rise to a cap- shaped protective cover or hydrophy Ilium as well as a pneumato- phore, and the under part becomes the primary nutritive polyp (Ayalmopsis, tig. 188). Since new buds give rise to leaf-shaped hydrophyllia, a small stock with FIG. 190.—Phi/sopJiora hyilruxfatica. Pn, Pneumatophore ; 5, nectocalyces arranged in double rows on the swim- ming column; T, dactylozoid ; P, polyp (nutritive individual) with tentacles, Sf; Kb, groups of nemato- cysts on the latter ; G, clusters of generative buds.
Size: 954px × 2097px
Photo credit: © Bookworm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: archive, book, drawing, historical, history, illustration, image, page, picture, print, reference, vintage
