The peripheral nervous system is minutely described by T.
The typical heteromerous thallus shows on section a peripheral, thin and therefore transparent, layer, the cortical layer, and centrally a mass of denser tissue the so-called medullary layer, between these two layers is the algal zone or gonidial layer (figs.
The former of these, representing the bottommoraine of the ice-sheet, are covered with Glacial and post-Glacial clays (partly of lacustrine and partly of marine origin) only in the peripheral coast-region - or in separate areas in the interior depressions.
Claus maintained that Baeyer's view was identical with his own, for as in Baeyer's formula, the fourth valencies have a different function from the peripheral valencies, being united at the centre in a form of potential union.
Jenn appeared in his peripheral then crossed to sit at the bench across from him.
In others the peripheral ends of the septa are united only by bars or trabeculae, so that the theca is perforate, and in many such perforate corals the septa themselves are pierced by numerous perforations.
They hadn't traveled far down the trail before she got a peripheral view of the building.
Microfilaria nocturna swarmed in the blood at night-time and disappeared from the peripheral circulation during the day, hiding away in the large vessels at the base of the lungs and of the heart.
The relatively peripheral position ii the stem of the pericycle is important in this connexmon.
In the peripheral ring farming increases, especially dairying; and manufacturing industries connected with the products of forests, farms and mines are developed.
These probably lessen fever by their action upon the nerve centres which regulate the temperature of the body, and partly by their peripheral action in causing the secretion of sweat.
Some of the most successful of the advances of medicine as a healing art have followed the detection of syphilitic disease of the vessels, or of the supporting tissues of nervous centres and of the peripheral nerves; so that, by specific medication, the treatment of paralytic, convulsive, and other terrible manifestations of nervous disease thus secondarily induced is now undertaken in early stages with definite prospect of cure.
While contemplating whether Freckles would be worth having to influence the other three or not, Jackson caught sight of someone in his peripheral vision.
While igneous and metamorphic crystalline rocks form the bulk of the Adirondack area, it is surrounded by a ring of ancient Palaeozoic sediments in which these peripheral lowlands have been developed.
In the one case they are entirely restricted to the neighbourhood of the boil or ulcer, whereas in the other there is a general infection of the body, the organisms spreading to all parts and being met with in the spleen, liver, bone-marrow, &c., and (rarely) in the peripheral circulation.
Those who work with living forms of which it is possible to obtain a large number of specimens, and those who make revisions of the provisional species of palaeontologists, are slowly coming to some such conception as that a species is the abstract central point around which a group of variations oscillate, and that the peripheral oscillations of one species may even overlap those of an allied species.
The two nuclei are successively divided from the egg nucleus in the usual way, but they frequently become absorbed in the peripheral protoplasm instead of being extruded from the egg-cell altogether.
Xx.; Id., " The Peripheral Nervous System of the Palaeoand Schizonemertini, one of the layers of the Body-wall," Quart.
A differentiation of the peripheral cytoplasm in the form of an ectoplasmic layer has been described in one or two instances, and it seems probable that in most Trypanosomes there is such a layer, although only poorly developed, as a rule, around the body generally.
Beri-beri is a dietetic deficiency disease which manifests itself by cardiac weakness with shortness of breath, swelling of the legs and peripheral neuritis with numbness of the limbs and weakness.
There are two pairs of specialized cerebral nerves innervating the praeoral lobe, and provided with peripheral ganglia placed near the termination of the smaller branches.
After the body of a spermatozoid has coalesced with the egg-nucleus the latter divides repeatedly and forms a mass of tissue which grows more vigorously in the lower part of the fertilized ovum, and extends upwards towards the apex of the ovum as a peripheral layer of parenchyma surrounding a central space.
The fauna of Turkestan belongs to the zoo-geographical domain of northern Asia, and is only differentiated by the presence of species which have disappeared from the peripheral parts of the Old World and now find a refuge in the remotest regions of the uninhabited plateau.
The Ascent of Water in Trees.The supply of water to the peripheral protoplasts of a tree is consequently of the first importance.
In the Cyanophyceae the contents of the cell are differentiated into a central colorless region, and a peripheral layer containing the chlorophyll and other coloring matters together with granules of a reserve substance called cyanophycin.
Reduction to hexamethylene compounds necessitates the disruption of three of the edges of the octahedron, the diagonal linkings remaining intact, or, in the plane projection, three peripheral linkages, the hexamethylene ring assuming the form (III); In 1888 J.
Within this muscular tube lies a parenchymatous tissue which may be uniform (Cestodes) or differentiated into a central or digestive, and a peripheral portion (some Turbellaria), or finally the central portion becomes tubular and forms the digestive sac (Trematodes), while the peripheral portion is separated from it by a space lined in some forms by a flattened epithelium (most Planarians).
This is the explanation of the repair of nerve trunks that have been severed, with consequent degeneration of the peripheral nerve fibres.
With reference to the existence of a chromatophore, he with others finds the colouring matter localized in granules in the peripheral region, but does not consider these individually or in the aggregate as chromatophores.
In the human subject, often due to streptococci, the process is similar, but the organisms are found especially in the capillaries of the internal organs and may not be detectable in the peripheral circulation during life.
The circular muscles usually form two chief portions, a peripheral wreath-muscle (Kranzmuskel), subdivided into four, eight or sixteen areas, and an oral ring-muscle round the mouth.
- Free medusae with rhopalia of the normal type; the exumbrella is divided by a circular, so-called coronal groove, into two parts, a central portion, which is conical, thimble-shaped, or domed in form, and a peripheral portion, the pedal zone, which bears the marginal lobes, tentacles and rhopalia; the pedal zone is subdivided into areas termed pedalia, from each of which arises a tentacle or rhopaliurn in the interspace between two adjacent lobes of the margin.
The Great Lakes are peculiar in receiving the drainage of but a sma]l peripheral land area, enclosed by an ill-defined water-parting from the rivers that run to Hudson Bay or the Gulf of St Lawrence on the north and to the Gulf of Mexico on the south.
It is certain that the centre of the cell, which is usually non-vacuolated, is occupied by protoplasm of different properties from the peripheral region; and A.
Fischer has further established the fact that the peripheral mass, which is a hollow sphere in spherical cells, and either a hollow cylinder or barrel-shaped body in filamentous forms, must be regarded as the single chromatophore of the Cyanophyceous cell.
In Gnetum Gnemon, as described by Lotsy, a mature embryo-sac contains in the upper part a large central vacuole and a peripheral layer of protoplasm, including several nuclei, which take the place of the archegonia of Ephedra; the lower part of the embryo-sac, separated from the upper by a constriction, is full of parenchyma.
(3) The theca or wall, which in many corals is not an independent structure, but is formed by the conjoined thickened peripheral ends of the septa.
In some corals the septa are solid imperforate plates of calcite, and their peripheral ends are either firmly welded together, or are united by interstitial pieces so as to form imperforate theca.
In the Fucaceae, on the other hand, there is a single prismatic apical cell situated at the bottom of a groove at the growing apex of the thallus, which cuts off cells from its sides to add to the peripheral, and from its base to add to the central permanent cells.
The significance of these phenomena, which present many minor modifications in different cases, is nol fully understood, but one purpose of the formation of phloem promontories and islands seems to be the protection of the sieve-tubes from crushing by the often considerable peripheral pressure that is e~ercised on the stems of these lianes.
Marsh also devised a form closely resembling that of Thomsen, inasmuch as the carbon atoms occupied the angles of a regular octahedron, and the diagonal linkages differed in nature from the peripheral, but differeng from Thomsen's since rupture of the diagonal and not peripheral bonds accompanied the reduction to hexamethylene.
In the effects of simpler poisons the recognition of unity in diversity, as in the affiliation of a peripheral neuritis to arsenic, illustrated more definitely this serial or etiological method of classifying diseases.
Many other diseases formerly regarded as primarily diseases of the nervous system are not such; but, by means of agents either introduced into the body or modified there, establish themselves after the affinities of these in contiguous associated parts of the structure, as in vascular, membranous or connective elements, or again in distant and peripheral parts; the perturbations of nervous function being secondary and consequential.
The grave palsies in such diseases as influenza, diphtheria, beriberi, or ensuing on the absorption of lead, are in the main not central, but due to a symmetrical peripheral neuritis.
More usually each cathamma is a wide triangular area, reducing the peripheral portion of the coelenteron to the four narrow radial canals and the ring-canal above described.
P. 392), who prefers to rotate the cathode at a speed that maintains a peripheral velocity of at least woo ft.
In certain species of Gnetum described by Karsten the megaspore contains a peripheral layer of protoplasm, in which scattered nuclei represent the female reproductive cells; in Gnetum Gnemon a similar state of things exists in the upper half of the megaspore, while the lower half agrees with the megaspore of Welwitschia in being full of prothallus-tissue, which serves merely as a reservoir of food.
True costae always correspond to the septa, and are in fact the peripheral edges of the latter.
It stretches forward as far as the brain, and in Carinella is again continued in front of it, whereas in the Heteronemertines the innervation of the anterior extremity of the head, in front of the brain, takes the form of more definite and less numerous branching stems. The presence of this plexus in connexion with the central stems, sending out nervous filaments amongst the muscles, explains the absence, in Pro-, Mesoand Heteronemertines, of separate and distinct peripheral nerve stems springing from the central stems innervating the different organs and body-regions, the only exceptions being the L.N.
When the salt is taken by the mouth, absorption is extremely rapid, the salt being present in the peripheral blood within ten minutes.
This is due to intense engorgement of the vessels brought about through these minute existing collateral channels and results in a peripheral congested zone round the infarct.
In heart disease the chief work of the latter half of the 19th century was, in the first quarter, such clinical work as that of William Stokes and Peter Mere Latham (1789-1875); and in the second quarter the fuller comprehension of the vascular system, central and peripheral, with its cycles and variations of blood pressure, venous and arterial.
The peripheral paren chyma gives rise to protonephridia, that is to coiled tubes commencing in pyriform cells containing a flame-like bundle of cilia and provided with branched outgrowths, and communicating with the exterior by long convoluted canals which open at the surface of the body.
The megaspore-nucleus divides repeatedly, and cells are produced from the peripheral region inwards, which eventually fill the sporecavity with a homogeneous tissue (prothallus); some of the superficial cells at the micropylar end of the megaspore increase in size and divide by a tangential wall into two, an upper cell which gives rise to the short two-celled neck of the archegonium, and a lower cell which develops into a large egg-cell.
In a few cases there is a special surface or epidermal layer, but usually all the outer layers of the stem are composed of brown, thick-walled, lignified, prosenchymatous, fibre-like cells forming a peripheral stereom (mechanical or supporting tissue) which forms the outer cortex.
The remaining tissue of the plant-body, a tissue that we must regard phylogenetically as the remnant of the undifferentiated tissu~ of the primitive thallus, but which often undergoes further different,iation of its own, the better to fulfil its characteristically vital functions for the whole plant, is known, from its peripheral position in relation to the primitively central conducting tissue, as (3) the cortex.
In Polia the connective tissue enclosed in the external muscular layer is eminently vacuolar - all the intermediate stages between such cells in which the vacuole predominates and the nucleus is peripheral and those in which the granular protoplasm still entirely fills them being moreover present.
Ordinarily, however, it is due to some peripheral irritation which is conducted by sensory nerves to the spinal cord and thence up to the sensory centre in the brain.