. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. rOLYPIFERA. permeates the stem, which thus seems to be nourished by the hundreds of little polypes that are constantly fishing for food. At certain periods of the year, besides the polype-bearing cells, other horny receptacles are developed, called the ovigerous vesicles (fig. 55, h), in which the ova are produced. The ovigerous vesicles are differently dis- posed according to the species, sometimes arising from the branches of the coralline, at others from the axillte formed by their sub- divisions ; their shape likewis
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. rOLYPIFERA. permeates the stem, which thus seems to be nourished by the hundreds of little polypes that are constantly fishing for food. At certain periods of the year, besides the polype-bearing cells, other horny receptacles are developed, called the ovigerous vesicles (fig. 55, h), in which the ova are produced. The ovigerous vesicles are differently dis- posed according to the species, sometimes arising from the branches of the coralline, at others from the axillte formed by their sub- divisions ; their shape likewise is very various, and sometimes they are covered with a little operculum, or lid, which closes the orifice of the vase-like vesicle during the maturation of the reproductive gemmules, and at last opens so as to permit their escape. These gemmu- liferous urns are, however, deciduous, and fall off after the development of the germs of reproduction is completed. Such being the general structure of the Sertularidae, we must now proceed to examine more minutely their intimate organisation. The stem of the Sertularian is composed of two layers, of which the exterior (Jig. 55, b), Fig. Diagram of Sertularian. a, inner or nutritive layer ; b, outer or tegu- mentary layer ; c, oral tentacles of the polype ; d, e, gemmules; /, polypiforin external capsule; h, ovi- gerous cell. or tegumentary layer, is of a dense horny tex- ture, while the internal, or nutritive layer (fig. 55, a), is of a soft pulpy character according to the pattern peculiar to the species; the tegu- mentary layer expands at appointed distances into the polype-cells (fig. 55, g) ; and it is from this layer likewise during the reproductive season that the ovigerous vesicles are deve- loped. The nutritive layer (fig. 55, a) it will be seen, not only lines the stem, but likewise penetrates into the polype-cells, where it be- comes continuous with the body of the con- tained polype, the structure of which clo
Size: 1388px × 1801px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, booksubjectanatomy, booksubjectphysiology, booksubjectzoology
