Page:The American Cyclopædia (1879) Volume XII.djvu/785

 OYER OYSTER 771 velopment of yeast and the oxidation of glu- ten ; the transformation of starch into glucose, and of glucose into alcohol ; also the further change of alcohol into acetic acid. The func- tion of animal respiration is a process by which the absorption of atmospheric oxygen by the blood is brought about in the capillaries of the lungs, in consequence of its affinity for a con- stituent of the blood globules, possessing the property, according to recent experiments of Hoppe-Seyler and Stokes, of absorbing an ad- ditional quantity of oxygen in a state of loose combination, by which the blood changes from a purple to a scarlet hue, and of again yield- ing it up to the tissues in the performance of their function of assimilation and elimination. This constituent of the blood globules is called by Hoppe-Seyler haemoglobine, and when in combination with oxygen oxy-heemoglobine. Prof. Stokes calls it, in its two conditions, pur- ple cruorine and scarlet cruorine. The per- formance of the functions of the nervous sys- tem is dependent upon the presence of oxygen in the blood, its deficiency causing an accu- mulation of carbonic acid and a state of coma. Respiration also includes the elimination of carbonic acid in the animal ; but in the plant, under the influence of sunlight, the absorption of carbonic acid, the fixation of carbon, and the elimination of oxygen. The action of gun- powder depends upon the weak combination of the oxygen element of nitre with nitro- gen, and its strong affinity for other ingredi- ents of the compound, as charcoal and sulphur, a union with which, at least with the charcoal, and a separation from the nitrogen, causes the evolution of an abundance of elastic gases. The drying of linseed oil and the hardening of paint is a process of oxidation, and could not take place without oxygen. The pro- cess of bronzing the surfaces of metals usu- ally consists either in oxidizing them, or in spreading on them another metallic compound which will undergo oxidation by exposure to the air. The action of sunlight on salts of silver causes them to decompose and the silver to become converted into black oxide; and photography, in one of its modes, depends upon the fixation of oxide of silver upon paper or other material. (See OZONE.) OYER (law Fr., a hearing, from Lat. audire, to hear). When one party declares on or oth- erwise pleads a deed, and founds his claim or rests his defence upon it, he must generally make profert of it, or in other words must aver in his pleadings that he produces the said deed in court. In practice, under a system of written pleadings, the production does not take place unless demanded by the adversary party, which is done by serving a written no- tice that he craves oyer. The party who has made profert then regularly grants oyer by giv- ing a copy of the instrument, and this enables the opposite party to set it forth in his subse- quent pleadings, and raise upon it any question which he may think of service to him in the case. It is only in this way that the deed is spread upon the record. If a party who regu- larly should make profert is unable for any reason to produce the instrument, he should not make profert, but should set forth in his pleading the facts which excuse it ; for if pro- fert is made, oyer must be granted when de- manded, or judgment may be entered up for the want of it. Oyer is not requisite in the case of unsealed instruments, or records ; but an executor or administrator who brings suit in his representative capacity must make pro- fert of the letters which are the foundation of his right to sue. OYER AND TERMINER, the technical name of the commission by virtue of which the judges in England take cognizance of and try criminal offences. The words were used in the commis- sion when it was written in Norman French ; and in English the authority is to " inquire, hear, and determine." In the United States courts for the trial of criminal causes have sometimes been designated courts of oyer and terminer, but the authority is conferred by statute and not by special commission. OYSTER, a marine acephalous mollusk, of the lamellibranchiate order and genus ostrea (Linn.). The shells are very irregular, inequi- valve, and lamellated, the right or upper shell being the smaller and flatter and moving for- ward with age, leaving a lengthening groove for the ligament exposed along the beak of the adhering valve, which is the left and lower, the deeper, and more capacious, and attached to foreign bodies by a calcareous growth from the shell itself. The shells are so variable in surface and shape that it would be difficult to describe them, and for the same reason it is almost impossible strictly to define the limits of the species; there is only one adductor muscle to hold the valves together, and the small ligament at the hinge is inserted into a little depression on each side, without teeth or projecting plates. The animal is very simple ; the mantle has a double fringe, and its lobes are widely separated, united only near the hinge ; there is no vestige of foot; respiration is effected by means of vascular gills or mem- branous plates attached to the inner surface of the mantle, to which water is brought by the ceaseless action of vibratile cilia; the mouth is jawless and toothless, but is provided with short labial processes separate from the gills for selecting food, consisting of minute parti- cles brought to it by the respiratory currents ; the intestine is comparatively short, with a few convolutions; the ventricle of the heart lies upon the rectum.. By most writers oysters have been considered hermaphrodite, but ac- cording to Siebold and others they are of sepa- rate sexes, though the females vastly prepon- derate, and are ovoviviparous ; they are sensi- ble of light, as is known by their closing the valves when reached by the shadow of an ap- proaching boat, and have numerous short, pe- dunculated, yellowish brown eyes between the