Praeoral ciliated ring, or prototroch.
The sense-cells form, in the first place, a diffuse system of scattered sensory cells, as in the polyp, developed chiefly on the manubrium, the tentacles and the margin of the umbrella, where they form a sensory ciliated epithelium covering the nerve-centres; in the second place, the sense-cells are concentrated to form definite sense-organs, situated always at the margin of the umbrella, hence often termed " marginal bodies."
Rarely are these ciliated, and then only in limited tracts.
Ray Lankester to the members of a series of tubes, proved in some cases to be excretory in nature, which exist typically to the number of a single pair in most of the segments of the Chaetopod body, and open each by a ciliated orifice into the coelom on the one hand, and by a pore on to the exterior of the body on the other.
In all these cases we have a duct which has a usually wide, always intercellular, lumen, generally, if not always, ciliated, which opens directly into the coelom on the one hand and on to the exterior of the body on the other.
Both series of organs consist essentially of a ciliated tube leading from the coelom to the exterior.
Quite independent of these are certain large dorsally situate funnel-like folds of the coelomic epithelium, ciliated, but of which no duct has been discovered leading to the exterior.
The body wall consists of an epidermis which secretes a delicate cuticle and is only ciliated in Aeolosoma, and in that genus only on the under surface of the prostomium.
The large prostomium is ciliated ventrally.
The efferent ducts are ciliated, and there is a patch of cilia at the point where they communicate with the cavity of each testis.
Each renal organ is a sac lined with glandular epithelium (ciliated cell, with concretions) communicating with the exterior by its papilla, and by ce, Cerebral ganglia.
It has simply been traced as far as the formation of a diblastula which acquires a ciliated band, and becomes a nearly spherical trochosphere.
A well-marked trochosphere is formed by the development of an equatorial ciliated band; and subsequently, by the disproportionate growth of the lower hemisphere, the trochosphere becomes a veliger.
Vr, Velum or circlet of ciliated cells.
B, The diblastula has become a trochosphere by the development of the ciliated ring y r (optical section).
This is a groove, the edges of which are raised and ciliated, lying near the branchial plume in the genera which possess that organ, whilst in Firoloida, which has no branchial plume, the osphradium occupies a corresponding position.
Beneath the ciliated groove is placed an elongated ganglion (olfactory ganglion) connected by a nerve to the supraintestinal (therefore the primitively dextral) ganglion of the long h, k, m, Stomach.
L', The ciliated communication of the renal sac with the pericardium.
Derm is coincident with the v, v, The ciliated band marking hindmost extremity of the out the velum.
When the middle and hinder regions of the blastopore are closing in, an equatorial ridge of ciliated cells is formed, converting the embryo into a typical trochosphere.
The ciliated band of the left side of the velar area is indicated by a line extending from v to v; the foot f is seen between the pharynx ph and the pedicle of invagination pi.
- Externally in all species a layer of ciliated cells forms the outer investment.
Only in one species, Carinella inexpectata, a step in advance has been made, in so far as in connexion with the furrow just mentioned, which is here also somewhat more complicated in its arrangement, a ciliated tube leads into the brain, there to end blindly amidst the nervecells.
No other intermediate stages have as yet been noticed between this arrangement and that of the Heteronemertini, in which a separate posterior brain-lobe receives a similar ciliated canal, and in which the oesophageal outgrowths have made their appearance and are coalesced with the nerve-tissue in the organ of the adult animal.
These posterior brain-lobes, which in all Heteronemertines are in direct continuity of tissue with the upper pair of principal lobes, cease to have this intimate connexion in the Metanemertini; and, although still constituted of (I) a ciliated duct, opening out externally, (2) nervous tissue surrounding it, and (3) histological elements distinctly different from the nervous, and most probably directly derived from the oesophageal outgrowths, they are nevertheless here no longer constantly situated behind the upper brain-lobes and directly connected with them, but are found sometimes behind, sometimes beside and sometimes before the brain-lobes.
These slits are continued into the ciliated duct, being at the same time themselves very strongly ciliated.
Two layers are specially obvious in its walls - the inner layer bordering the lumen being composed of smaller ciliated cells, the outer thicker one containing numerous granular cells and having a more glandular character.
Each consists of a more or less coiled, ciliated, longitudinal canal, which on its external surface gives origin to one or more transverse canals, which pass to the exterior and open a little way behind the mouth on the sides of the body.
Two pairs of invaginations of B the skin, which originally are called the prostomial and metastomial disks, grow round the intestine, finally fuse together, and form the skin and mus- cular body-wall of the future Nemertine, which afterwards becomes ciliated, frees itself from the pilidium investment and develops into the adult worm without further metamorphosis.
Of these divisions of the coelom the first two communicate with the exterior by means of a pair of ciliated pore-canals placed at the posterior end of their respective segments.
- At the base of the epidermis (which is in general ciliated) there is over the entire surface of the body a layer of nervefibres, occurring immediately outside the basement-membrane which separates the epidermis from the subjacent musculature.
In addition to this ciliated band the form of the Tornaria is quite characteristic and unlike the adult.
The head is produced into ciliated arms bearing tentacles.
In addition to these, there exists in the interior of the dorsal valve of some genera a variously modified, thin, calcified, ribbon-shaped skeleton for the support of the ciliated arms, and the form of this ribbon serves as one of the chief generic characters of both recent and extinct forms. This brachial skeleton is more developed in some genera than in others.
Externally on two sides and on the inner surface the tentacles are ciliated, and the cilia are continued across the 5 gutter to the lip and even on the outer surface of the latter.
The great arm-sinus of each side of the lophophore lies beneath the fold or lip which together with the tentacles forms the ciliated groove in which the mouth opens.
The stomach, oesophagus and intestine are ciliated on their inner surface.
The ectodermal cells are large, ciliated, and amongst the ciliated cells glandular cells are scattered.
A large number of specimens of a species are usually found together, since their only mode of spreading is during the ciliated larval stage, which although it swims vigorously can only cover a few millimetres an hour; still it may be carried some little distance by currents.
The egg gives rise to an oval larva, one half of which is ciliated and bears gland-cells, the opposite end carrying ten hooks.
8, D) capable of living freely in water for at least a week (Bothriocephalus), which then, if eaten by a stickleback, throws off its ciliated envelope, and creeps by the aid of the hooks through the intestinal wall into the body-cavity of the fish.
D, ciliated embryo of B.
The chief peculiarities that distinguish Trematodes from their free-living allies, the Turbellaria, are the development of adhering organs for attachment to the tissues of the host; the replacement of the primitively ciliated epidermis by a thick cuticular layer and deeply sunk cells to ensure protection against the solvent action of the host; and (in one large order) a prolonged and peculiar life-history.
Long) larva capable of swimming freely for a short time by the aid of five girdles of ciliated cells.
The ciliated stage is only capable of free life for five or six hours, and if at the end of that time it has not encountered and attached itself to a minnow, it dies.
The life-history of Schistostomum haematobium is still unknown, but the difficulty in obtaining developmental stages in any of the numerous intermediate hosts that have been tried suggests that the ciliated larvae may develop directly in man and either gain access to him by the use of impure water for drinking or may perforate his skin when bathing.
The ciliated larva escapes from the egg into the water and enters an intermediate host (leech, mollusc, arthropod, batrachian or fish) where it undergoes a metamorphosis into a second stage in which most of the adult organs are present.
They may be defined as aquatic animals, forming colonies by budding; with ciliated retractile tentacles and a U-shaped alimentary canal.
The polypide consists of a "lophophore" bearing a series of ciliated tentacles by which Diatoms and other microscopic bodies are collected as food, of a U-shaped alimentary canal, and of a central nervous system.
This is followed by the atrophy of many of the larval organs, including the brain, the sense-organ and the ciliated ring.