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Updated: May 26, 2025
This process of absorption is probably accomplished in the interradial or ciliated chambers, more probably in the former, as the latter are generally considered excretory in function. Lime or silica must also be absorbed from the water by most sponges in order to make up the skeleton. The skeleton of calcareous sponges consists of a number of spicules composed of carbonate of lime.
Cell contents uniform, dense, cell division accompanied by circumscissile debiscence of the parent cell, producing rings on the filaments. Reproduction by zoospores formed of the whole contents of a cell, with a crown of numerous cilia; resting spores formed in sporangial cells after fecundation by ciliated spermatozoids formed in antheridial cells.
In the turbellaria we find for the first time a true body-wall distinct from underlying organs. The outer layer of this is a ciliated epithelium or layer of cells. Under this an elastic membrane may occur. Then come true body muscles, running transversely, longitudinally and dorso-ventrally.
With an ivory paper-knife scrape the back of the tongue or the inside of the lips or cheek; place the substance thus obtained upon a glass slide; cover it with a thin cover-glass, and if necessary add a drop of water. Examine with the microscope, and the irregularly formed epithelial cells will be seen. Experiment 2. To examine ciliated epithelium.
The same, showing the other organs. g brain, au eye, na olfactory pit, n nerves, h testicles, male symbol male aperture, female symbol female aperture, e ovary, f ciliated epiderm. Next to the ancient stem-group of the Turbellaria come a number of more recent chordonia ancestors, which we class with the Vermalia or Helminthes, the unarticulated worms.
A ciliated sphere like the Volvox has no parts of its periphery unlike other parts; and it is not to be expected that it should have; seeing that as it revolves in all directions, it does not, in traversing the water, permanently expose any part to special conditions.
This latter is provided above with two slender six-jointed antennae, two very large faceted eyes at the side, and three ocelli forming a triangle. The last four segments, of decreasing breadth, are retractile beneath the carapax, as is also the broad plume that terminates them, and which is formed of three short, transparent, and elegantly ciliated bristles.
Now, if you expect me to hold forth in a "scientific" way about my tree-loves, to talk, for instance, of the Ulmus Americana, and describe the ciliated edges of its samara, and all that, you are an anserine individual, and I must refer you to a dull friend who will discourse to you of such matters.
The walls of the larynx contain strips and plates of cartilage; while the nostrils and the pharynx are kept open by their bony surroundings. Cilia, n. Nucleus. The air passages are kept clean by cells especially adapted to this purpose, known as the ciliated epithelial cells. They line the mucous membrane in most of the air passages, and are so placed that the cilia project into the tubes.
The excretory system consists of a pair of tubes discharging through the sides of the body-wall, and having each a ciliated, funnel-shaped opening in the perivisceral cavity. These have received the name of nephridia. Through these also the eggs and spermatozoa are discharged. The reproductive organs are modified patches of the peritoneum, or lining of the perivisceral cavity.
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