. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. MORPHOLOGY AND DEVELOPMENT OF EUDENDRIUM. 29 (Fig. 3). This is produced by the active proliferation of the ectoderm adjoining the egg. For a time the cells differ little from those of the hydranth ectoderm. Soon the entoderm just above the egg begins to form a blunt tube of columnar cells opening into the enteric cavity. The end grows outward be- tween egg and mesoglosa. Growth of the base aids in carrying the egg out from the general surface of the hydranth (Fig. 4.) Continued elongation brings the end of the tube over the
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. MORPHOLOGY AND DEVELOPMENT OF EUDENDRIUM. 29 (Fig. 3). This is produced by the active proliferation of the ectoderm adjoining the egg. For a time the cells differ little from those of the hydranth ectoderm. Soon the entoderm just above the egg begins to form a blunt tube of columnar cells opening into the enteric cavity. The end grows outward be- tween egg and mesoglosa. Growth of the base aids in carrying the egg out from the general surface of the hydranth (Fig. 4.) Continued elongation brings the end of the tube over the top of the egg and down the outside where it divides sending a branch inward and upward on either side to form the coil. Viewed from the side the spadix now looks like a spiral of one and a half turns. Linear growth of the spadix is nearly complete when the egg has one third of its mature diameter. It stands out from the surface at first, but in time becomes flattened against the egg. The ectoderm undergoes a gradual change to a thin tough sheath covered by a tenuous perisarc. It passes over the spadix and else- where is separated from the egg by the mesoglcea only. Together with the base of the spadix, it forms the stalk of the gono- phore. While the spadix is developing the egg rounds out into a sphere and rapidly en- larges. Its increase in bulk is due to the formation of large granules of deutoplasm. Weismann, 'Si1, describes a contraction and expansion of the spadix in the living gonophore of Corync piisilla which he thinks functions to move the nutritive fluid, used by the growing egg. Variations in the diameter of spadix lumen of E. ramosnm sug- gest that the same motion occurs in it. There can be no doubt that the egg absorbs nourishment through the walls of the spadix, as has been pointed out by others. Dr. Hargitt has suggested that the flattening of the spadix is due to the absorption by the egg of the contents of its FIG. Please note that these images ar
Size: 868px × 2877px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
