This idea, however, was found to be incorrect since when the stem was cut into two or more pieces each piece formed a polyp at once at its oral pole and regenerated the aboral polyps also, but again with the usual delay.
Miss Bickford[155] found that the difference in time between the formation of the two polyps disappears also when the piece cut from the stem becomes so small that it is of the order of magnitude of a single polyp.
In the tanks it is far commoner to find young four-rayed polyps on Vivipara than individuals with five or six rays; but the adults of the species are far less prone to change their position than are the young.
Green (chlorophyll) Minute green bodies contained in cells corpuscles of polyps or other animals and representing a stage in the life-history of an alga (Chlorella).
The specific name refers to the fact that the ends of the rhizomes from which the polyps arise are frequently free and elongate, for the young polyp at the tip apparently takes some time to assume its adult form.
Unequal vertical division occurs when the column is divided vertically in such a way that the two resulting polyps are unequal in size.
In captivity the polyps seek the bottom of any vessel in which they are contained, if sunlight falls on the surface of the water.
Probably it never moves in a straight line, but if direct sunlight falls on one side of a glass aquarium, the polyps move away from that side in a much less erratic course than is usually the case.
They differ from these polyps in very much the same way as, but to a greater degree than they do from the winter phase of their own race, and I have therefore no doubt that H.
The dark green colour of some polyps is, however, less easily explained.
But although the bank cannot be raised higher it can still be extended on all sides; and so the little polyps go working on, year after year, till at last the results of their labor are almost too wonderful to realize.
Baby polyps sprout out all over their bodies, and these, instead of swimming about for a few days like those which are hatched from eggs, remain fixed where they are for the whole of their lives.
In such a case the polyps have to build out at sea, instead of close into the land, and there is a kind of moat between the coral bank and the shore.
We will not talk about that just now, but wait till we take our excursion to the rocky shore, where we shall find barnacles and corallines and sea-mats and polyps bigger and better than here.
The polyps which hatch out from eggs swim about for some little time quite freely.
The coral produced by a single community of polyps grows chiefly upward; but multitudes of distinct communities often live so near together that the small lateral growth of each brings them into contact.
Reef-building polyps do not live below the depth of one hundred or one hundred and twenty feet, and hence require a foundation near the surface.
The polyps are cut out, and frequently parts of the turbinated bone and septum as well, in order to open the air passages.
In some polyps the tentacles are webbed at the base, and it was supposed that a medusa was a polyp of this kind set free, the umbrella being a greatly developed web or membrane extending between the tentacles.
Trophosome, polyps with two whorls of tentacles, both filiform.
It is convenient to distinguish buds that give rise to polypsfrom those that form medusae.
The polyps may be solitary, or form colonies, which may be of the spreading or encrusting type, or arborescent, and then always of monopodial growth and budding.
It has been shown above that polyps are budded only from polypsand that the medusae may be budded either from polyps or from medusae.
Whereas primitively any polyp in a colony may produce medusa-buds, in many hydroid colonies medusae are budded only by certain polyps termed blastostyles (fig.
The germ-cells are capable of extensive migrations, not only in the body of the same polyp, but also from parent to bud through many non-sexual generations of polyps in a colony (A.
In the Calyptoblastea, where the polyps are protected by special capsules of the perisarc, the gonothecae enclosing the blastostyles differ from the hydrothecae protecting the hydranths (fig.
Trophosome encrusting with hydranths of Bougainvillea-type, polyps differentiated into blastostyles, gastrozoids and dactylozoids; gonosome free medusae or gonophores.
Trophosome, polyps with an upper circlet of numerous capitate tentacles, and a lower circlet of filiform tentacles.
The living rays or flower-like face are the features in which this encased worm resembles the coral polyps on the one hand and the houseless beche-de-mer on the other.
From the sea water the polyps secrete calcium carbonate and build it up into the stony framework which supports their colonies.
As the reef widens, the polyps of the circumference flourish, while those of the inner belt are retarded in their growth and at last perish.
It is in this region that coral reefs and other great accumulations of limestone, formed from the skeletons of polyps and mollusks, most abundantly occur.
At these points, if the water have a tropical temperature, we invariably find a vast and rapid development of marine animals and plants, of which the coral-making polyps are the most important.
The circular reef of coral, the work of ancient Polyps, foreshadows the atolls of the great ocean, for it was during the Jurassic period that the Polyps of the ancient world were most active in the production of coral-reefs and islets.
They just reach the level of the waters, for the polyps perish as soon as they are so far above the surface that neither the waves nor the flow of the tides can reach them.
We have already remarked that these aggregations of Polyps are often met with at a great depth in the strata.
In this liquid and chemically calcareous medium, the Foraminifera and Polyps of all forms swarmed, forming an innumerable population.
In reality the sponge is a colony of little animals called polyps which occupy a sort of apartment house together, rearing families just as other animals do.
When the animal is alive water is kept flowing constantly through these channels by means of minute, hair-like appendages, which the little polyps agitate.
The coral, sponge, and polyps are instances of this order, which also includes the Infusorial Animalcules.
Illustration] OF these Fresh-water Polypi, only a few kinds are known, but the sea nourishes a multitude of species which closely resemble the Hydras in their structure, from hence called Hydroid Polyps by Cuvier and many other naturalists.
Polyps with Polyparies, the latter including all the various compound zoophytes, with the Sponges.
Here the tiny polyps have built an island for people who are so much larger and stronger than themselves, and the seeming destruction of their upper walls was only a better preparation for the reception of these distinguished visitors.
The common tissue which unites the polyps or zooids of a compound anthozoan or coral.
The common soft tissue which unites the polyps of a compound hydroid.
Thus some of the little "coralline polyps" and other most beautiful little marine flower-like polyps attached to rocks, weeds, and shells in the sea reproduce by budding and division.
In the sea pen the polyps are arranged along the branches so that a fluffy fan or an ostrich plume is imitated.
In the Atlantic, as far north as Long Island Sound, where the water is often icy cold, is found the beautiful Astrangia, a coral in which the polyps are pure white and about five one-hundredths of an inch in length.
The starlike spots are the polyps with their tentacles outspread as in feeding.
Which of thepolyps you have studied shows the greatest differentiation?
How may polyps in colonial forms differ from polypswhich live singly?
The lowest in structure among thePolyps are not Corals, but the single, soft-bodied Actiniae.
If, now, we compare this structural gradation amongPolyps with their geological succession, we shall find that they correspond exactly.
In this coral thepolyps are of a milk-white colour.
The growing points of white branching corals (Madrepores) are frequently tipped with vivid purple, and the tiny polyps themselves are glowing gem-stars.
The polyps of the madrepores resemble flowers when their upper disc is expanded and their feelers are out in the water.
From these observations it was obvious to him that the utmost depth at which the coral polyps can construct reefs is between twenty and thirty fathoms.
One of the most pleasing forms is found in the Plantain Madrepore, where the polypsare arranged in tufts.
Sea-polyps from the Atlantic: voyage of the Challenger, i.
Passing on to higher forms of animal life, the polyps and acalephae of the older authors, now classified as the Coelenterata, we find creatures of a superior organisation to those lately under notice.
The skin of thepolyps contains, at certain fixed spots, groups of similar spicula, but much more minute.
Most of the polyps form stocks (cormi), the individuals shooting out buds which remain joined to the mother animal.
The tube is branched, and the orifices from which the polyps expand usually dilate into cups or cells.
Mediterranean, the polyps are of a greyish colour, the tentacula streaked with black.
Between the nursing polyps are placed in pairs the reproductive individuals, having the form of an elongated tube very dilatable, and closed at the free end.
This trunk carries in like manner polyps placed at regular intervals forming isolated groups, provided each with its protecting plates.
Notwithstanding the philosophic serenity which Bennet recommends, the fact of new individuals resulting from dividing these fresh-water polyps was always a subject of profound astonishment, and of never-ending meditation.
The Coralline polyps have no will; the Pennatula have.
At the end of fifteen days the colony, which has been forming under our eyes, consists of two polyps and a bud, which already indicates a third polyp.
Let us pause an instant over the soft and fleshy bark in which the polyps are engaged.
The arms of the polyps are at times subject to violent agitation: the tentacula become much excited.
The polyps are composed generally of a hidden portion more or less tubular, and of a star-like portion more or less displayed.
The Medusæ comprehend, not only the animals so designated in the days of Cuvier under that name, but also the polyps known as Tubulariadæ and Campanulariadæ.
The body of these polyps presents marginal fringes furnished with vibratile cilia, which are swimming organs.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "polyps" in a variety of sentences. We hope that you will now be able to make sentences using this word.
