. Zoology : for students and general readers . Zoology. CHAPTER III. BEANCH -CCELENTEEATA (Hydeoids, Fishes and Polyps). Jelly- â i:/"'. General Characters of Coelenterates.âIn this branch, which is represented by animals hke the Hydra (Fig. 36) and Tuhularia (Fig. 35), the body consists of three cell-layers, surrounding a definite, single, digestive cavity, the mouth of the cavity being surrounded by a circle of tentacles, which are hol- low and connect directly with the stomach. The latter, however, is only partly differentiated or set apart from the body, hence the name Ccelenter
. Zoology : for students and general readers . Zoology. CHAPTER III. BEANCH -CCELENTEEATA (Hydeoids, Fishes and Polyps). Jelly- â i:/"'. General Characters of Coelenterates.âIn this branch, which is represented by animals hke the Hydra (Fig. 36) and Tuhularia (Fig. 35), the body consists of three cell-layers, surrounding a definite, single, digestive cavity, the mouth of the cavity being surrounded by a circle of tentacles, which are hol- low and connect directly with the stomach. The latter, however, is only partly differentiated or set apart from the body, hence the name Ccelenterata (Greek, uoikoi, hidden, and evrepov^ digestive tract). From the stomach often radiate water-vascular canals, no blood-system yet appearing thus far in the animal kingdom, the products of digestion reaching the tissues from the smaller branches of the primary water-vascular canals. The nervous system is either absent, or in different gTades of development, from the iso- lated nervo-muscular cells of Hydra and the scattered nerve-cells of an Actinia, to the continuous ganglion- ated nervous ring of the minute jelly-fish such as Sarsia. These animals display a striking amount of radial symmetry, the organs and body being dis- posed in a radiate manner around a central vertical axis, in. Pig. 35.âAHydroid. Tu6u- laria. m, medusa budw ; cf, tentacles; p, proboscis.â From Tenney's Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Packard, A. S. (Alpheus Spring), 1839-1905. New York : Henry Holt
Size: 977px × 2559px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1870, booksubjectzoology, bookyear1879
