The majority of birds possess a pair of internal tympaniform membranes forming the inner or median walls of the bronchi, which are there furnished with semi-rings only.
These vascular membranes are called the lateral septa.
This section comprehends three species only, known as Phalaropes or swimming sandpipers, which are distinguished by the membranes that fringe their toes, in two of the species forming marginal lobes,' and by the character of their lower plumage, which is as close as that of a duck.
When the connecting string is held taut and sounds, such as those of ordinary speech, are produced in front of one of the membranes, pulses corresponding to the fluctuations of the atmospheric pressure are transmitted along the string and communicated to the other membrane, which in its turn communicates them to the air, thus reproducing the sound.
Ical tele- Two disks of thin metal, or two stretched membranes, each furnished with a mouthpiece, are connected together by a thin string or wire attached at each end to the centres of the membranes.
A good example may be made with two cylindrical tin cups; the bottoms form the membranes and the cups the mouthpieces.
Free-swimming organisms without cell-membranes exist in both, and from them series of forms can be traced in both directions.
Both cuticularized and suberized membranes are insoluble in cuprammonia, and are colored yellow or brown in a soltition of chlor-iodide of zinc. It is probable that the corky or suberized cells do not contain any cellulose (Gilson, Wisselingh); whilst cuticularized cells are only modified in their outer layers, cellulose inner layers being still recognizable.
The suberized and cuticularized cell-walls appear to contain a fatty body called suberin, and such cell-walls can be stained red by a solution of alcanin, the lignified and cellulose membranes remaining unstained.
They are very thin-walled membranes, very poor in blood-vessels, formed by the bulged-out pleural or peritoneal covering of the lungs, through the parabronchial tubes of which they are filled with air.
Essential are vibrating membranes between the cartilaginous framework, and next, special muscles for regulating the tension.
External tympaniform membranes exist, with great variations, between the specialized one or two last tracheal and some of the first bronchial rings.
According to the position of the chief sound-producing membranes, three types of syrinx are distinguishable: - (i) Tracheo-bronchial, by far the commonest form, of which the two others are to a certain extent modifications.
The essential feature is that the proximal end of the inner membranes is attached to the last pair of tracheal rings; outer tympaniform membranes exist generally between the 2nd, 3rd and 4th bronchial semi-rings.
Inner and outer membranes may exist on the bronchi.
Elastin occurs either as thick strands or as membranes; it constitutes the " elastic tissue " of the anatomist.
Applied externally lead salts have practically no action upon the unbroken skin, but applied to sores, ulcers or any exposed mucous membranes they coagulate the albumen in the tissues themselves and contract the small vessels.
Internally lead has an astringent action on the mucous membranes, causing a sensation of dryness; the dilute solution of the subacetate forms an effective gargle in tonsillitis.
By mucoid is understood a soft gelatinous substance containing mucin, or pseudomucin, which is normally secreted by the epithelial cells of both the mucous membranes and glands.
These soluble salts combine with the albumins in the body, and are deposited as minute granules of silver albuminate in the connective tissue of the skin papillae, serous membranes, the intima of arteries and the kidney.
The terrible nervous sequels of some forms of inflammation of the membranes of the brain, again, are due primarily to microbic invasion rather of the membranes than of their nervous contents; and many other diseases may be added to this list.
The coloration is generally sombre, but to this there are exceptions; the fruit-bats are brownish yellow or russet on the under surface; two South American species are white; Blainville's chin-leafed bat is bright orange; and the Indian painted bat (Cerivoula pieta) with its deep orange dress, spotted with black on the wing-membranes, has reminded observers of a large butterfly.
The sense-organs are highly developed; the wing-membranes are exceedingly sensitive; the nose-leaf is also an organ of perception, and the external ear is specially modified to receive soundwaves.
And the attention of modern psychologists is now being drawn to his doctrine of the relation of the elements of the universe to the membranes of the body.
It possesses only slight influence over the heart and respiration, but it has a specific effect on mucous membranes as the elimination of the drug takes place largely through the lungs, where it aids in loosening bronchial secretions.
But other relations between the different properties of solutions have been investigated by another series of conceptions which we shall proceed to develop. Some botanical experiments made about 1870 suggested the idea of semi-permeable membranes, i.e.
Membranes which allow a solvent to pass freely but are impervious to a solute when dissolved in that solvent.
Artificial membranes are seldom or never perfectly semi-permeable - some leakage of solute nearly always occurs, but the imperfections of actual membranes need no more prevent our use of the ideal conception than the faults of real engines invalidate the theory of ideal thermodynamics founded on the conception of a perfect, reversible, frictionless, heat engine.
Experiments with membranes of copper ferrocyanide have verified this result for solutions of cane-sugar of moderate dilutions.
Although even good membranes of copper ferrocyanide are rarely perfectly semi-permeable, and in other membranes such as indiarubber, &c., which have been used, the defects from the theoretical values of the equilibrium pressure are very great, yet, in the light of the exact verification of theory given by the experiments described above, it is evident that such failures to reach the limiting value in no wise invalidate the theory of osmotic equilibrium.
The osmotic pressures of strong sugar solutions were measured successfully by a direct method with semi-permeable membranes of copper ferrocyanide by Lord Berkeley and E.
The conceptions of osmotic pressure and ideal semi-permeable membranes enable us to deduce other thermodynamic relations between the different properties of solutions.
The passage of dissolved substances through animal and vegetable membranes was the subject of many early experiments.
It was found that substances like mineral salts, which crystallize well from solution, passed such membranes with comparative ease, while the jelly-like substances such as albumen passed with extreme slowness if at all.
As in other cell-walls, so here the older membranes may be altered by deposits of various substances, such as resin, calcium oxalate, colouring matters; or more profoundly altered throughout, or in definite layers, by lignification, suberization (Trametes, Daedalea), or swelling to a gelatinous mucilage (Tremella, Gymnosporangium), while cutinization of the outer layers is common.
That such enzymes are formed in the protoplasm is evident from the behaviour of hyphae, which have been observed to pierce cell-membranes, the chitinous coats of insects, artificial collodion films and layers of wax, &c. That a fungus can secrete more than one enzyme, according to the materials its hyphae have to attack, has been shown by the extraction of diastase, inulase, trehalase, invertase, maltase, raffinase, malizitase, emulsin, trypsin and lipase from Aspergillus by Bourquelot, and similar events occur in other fungi.
P. Pfeffer (Osmotische Untersuchungen, Leipzig, 1877) was the first to obtain satisfactory measurements of osmotic pressures of cane-sugar solutions up to nearly I atmosphere by means of semi-permeable membranes of copper ferrocyanide.
The serous membranes show petechiae and haemorrhages.
The substance of the brain, spinal cord and nervetrunks is normal, but the membranes are engorged.
The most important applications of the theory of vibrations are to the case of continuous systems such as strings, bars, membranes, plates, columns of air, where the number of degrees of freedom is infinite.
They pass more readily through mucous membranes, but almost every one of these is provided not only with a coating of mucus, which obstructs their passage, but with some reflex mechanism which tends to remove them.
For the purpose of checking the inflammatory processes and lessening discharge from mucous membranes astringents are employed.
C. Marsh, showing extent of flying membranes ('y nat.
They dissolve in water to form solutions, which do not penetrate parchment membranes, hence the name colloidal.
The treatment consists in the use of solutions of common salt, followed by copious draughts of milk or white of egg and water or soap in water, in order to dilute the poison and protect the mucous membranes of the oesophagus and stomach from its action.
Be less toxic. Glycothymolin is a proprietary preparation, used in the treatment of catarrhal conditions of mucous membranes, while a mixture of naphthalene, camphor and thymol is sold under the name of thymolin.
Subjection to the temperature of boiling water for, say, half an hour seemed an efficient mode of sterilization, until it was discovered that the spores of bacteria are so involved in heat-resisting membranes, that only prolonged exposure to dry, baking heat can be recognized as an efficient process of sterilization.
Formerly the animal oils and fats were obtained by heating the tissues containing the oils or fats over a free fire, when the cell membranes burst and the liquid fat flowed out.
The cellulose membranes showed traces of subjection to butyric fermentation, such as is produced at the present day by Bacillus Amylobacter; he also claimed to have detected the organism itself.
They are readily absorbed into the blood, and they are excreted chiefly by the kidneys in a more or less altered form, and probably also by the different mucous membranes, and even by the skin.
The outer membranes are spread out between two or more successive bronchial semi-rings, a distance from the trachea which is, in typical cases, devoid of sounding membranes; some Cuculi, Caprimulgi, and some owls.
The lower portion of the trachea consists of thin membranes, about half a dozen of the rings being very thin or deficient.
Heider bryonic membranes are vestigial or entirely wanting.
Graber, however (1889), of the embryonic membranes has lately been shown by Heymons.
In moths and certain saw-flies there is no rupture of the membranes; the Russian zoologists Tichomirov and Kovalevsky have described the growth of both amnion and embryonic ectoderm around the yolk, the embryo being thus completely enclosed until hatching time by both amnion and serosa.
In the stomach it casts its membranes and becomes mobile, bores through the stomach walls and encysts usually in the bodycavity of its first and invertebrate host.