Page:Encyclopædia Britannica, Ninth Edition, v. 18.djvu/118

 106 X Y O Y S axial tubes, while oxygen is being blown into the hydrogen ilaine through the central tube. The calorific effect of a Hare s lamji is of course less than that of Newman s, but still exceeds that of any ordinary fire ; it is inferior only to that of the electric arc. Platinum fuses in the ilaine with facility, and silica and alumina (though absolutely infusible in the metallurgist s sense) run into viscid glasses. Notwithstanding its enormous temperature, an oxy- hydrogen flame emits only a feeble light; but this arises only from the absence in it of good radiators. We need only communicate its- high temperature to some non-volatile and infusible solid, and a considerable portion of the heat is converted into radiant energy which streams forth as a dazzling white light. In the oxyhydro- gen lamp as used in connexion with the magic lantern or the &quot;solar&quot; microscope, a bit of lime fixed to an upright wire serves as a radiator. Magnesia is said to be better, and it has been said that zircouia excels both. Now that the electric light is com ing into general use, the oxyhydrogen lamp as a source of light will soon be a thing of the past. It is sure, however, to survive as a powerful producer of intense heat, and not for scientific purposes only. Thanks to the pioneering activity of Deville and Debray, it has found its way into the platinum works, and will hold its ground there until it may be superseded by the electric arc. The soldering together of the several parts of a platinum apparatus is now done &quot; autogynically &quot; (i.e., without the interposition of any foreign &quot; solder ) by means of the oxyhydrogen blowpipe, a great improvement over the old process of soldering with gold, which stripped the platinum-work of its most valuable character, namely, its relative infusibility. (W. D. ) OXYNOTUS, the name of a genus of birds now ascer tained to be peculiar to two of the Mascarene Islands Mauritius and Reunion (Bourbon) where the name of Cuisinier is applied to them, and remarkable for the fact, almost if not quite unique in Ornithology, 1 that, while the males of both species are almost identical in appearance, the females are wholly unlike each other. Though the habits of the Mauritian species, 0. rufiventer, have been very fairly observed, there seems to be nothing in them that might account for the peculiarity. The genus Oxynotus is generally placed in the group known as Campophagidx, most or all of which are distinguished from the Laniidx (to which they seem nearly allied) by the feathers on the lower part of the back and on the rump having the basal portion of the shaft very stiff and the distal portion soft a structure which makes that part of the body, on being touched by the finger, feel as though it were beset with blunt prickles. Hence the name of the genus conferred by Swainson, and intended to signify &quot; prickly back.&quot; The males, which look rather like miniature Grey Shrikes (Lanius excubitor and others), are except on close exami nation, when some slight differences of build and shade become discernible quite indistinguishable ; but the female of the one species has a reddish-brown back, and is bright ferruginous beneath, while the female of the other species is dull white beneath, transversely barred, as are the females of some Shrikes, with brown. Both sexes of each species, and the young of one of them, are described and figured in TJie Ibis for 1866 (pp. 275-280, pis. vii. and viii.). (A. N.) OYER AND TERMENER, in English law, is one of the commissions by which a judge of assize sits (see ASSIZE). By the commission of oyer and terminer the commissioners (in practice the judges of assize, though other persons are named with them in the commission) are commanded to make diligent inquiry into all treasons, felonies, and misdemeanours whatever committed in the counties specified in the commission, and to hear and determine the same according to law. The inquiry is by means of the grand jury ; after the grand jury has found the bills submitted to it, the commissioners proceed to hear and determine (oyer and terminer) by means of the petty jury. The words oyer and terminer are also used to 1 The only other instance cited by Darwin (Descent of Man, ii. pp. 192, 193) is that of two species of Paradisea; but therein the males differ from one another to a far greater degree than do those of Oxynotus. denote the court which has jurisdiction to try offences within the limits to which the commission of oyer and terminer extends. By 7 Anne c. 21 the crown has power to issue commissions of oyer and terminer in Scotland for the trial of treason and mis- prision of treason. Three of the lords of justiciary must be in any such commission. An indictment for either of the offences mentioned may be removed by certiorari from the court of oyer and terminer into the court of justiciary. In the United States oyer and terminer is the name given to courts of criminal jurisdiction in some States, e.g., New York, New Jersey, Pennsylvania, and Georgia. OYSTER. The use of this name in the vernacular is equivalent to that of Ostrea in zoological nomenclature ; there are no genera so similar to Ostrea as to be confounded with it in ordinary language. Ostrea is a genus of Lamel- libranch Molluscs, belonging to the third order Monomya, the valves of its shell being closed by a single large adductor muscle. The degeneration produced by sedentary habits in all lamellibranchs has in the oyster reached its most advanced stage. The muscular projection of the ventral surface called the foot, whose various modifications characterize the different classes of Mollusca, is almost entirely aborted. The two valves of the shell are unequal in size, and of different shape ; the left valve is larger, thicker, and more convex, and on it the animal rests in its natural state. This valve, in the young oyster, is attached to some object on the sea-bottom ; in the adult it is some times attached, sometimes free. The right valve is flat, and smaller and thinner than the left. In a corresponding manner the right side of the animal s body is somewhat less developed than the left, and to this exterlt there is a departure from the bilateral symmetry characteristic of lamellibranchs. The organization of the oyster, as compared with that of a typical lamellibranch such as Anodon (see MOLLUSCA), is brought about by the reduction of the anterior part of the body accompanying the loss of the anterior adductor, and the enlargement of the posterior region. The pedal ganglia and auditory organs have disappeared with the foot, at all events have never been detected ; the labial ganglia are very minute, while the parieto-splanchnic are well developed, and constitute the principal part of the nervous system. According to Spengel the pair of ganglia near the mouth, variously called labial or cerebral, represent the cerebral pair and pleural pair of a gastropod combined, and the parieto-splanchnic pair correspond to the visceral ganglia, the commissure which connects them with the cerebro-pleural representing the visceral commissure. Each of the visceral ganglia is connected or combined with an olfactory ganglion underlying an area of special ized epithelium, which constitutes the olfactory organ, the osphradium. This view (which, it may be pointed out, differs from that given under MOLLUSCA) alone admits of a satisfactory comparison between the lamellibranch and the gastropod ; if the parieto-splanchnic were merely an olfactory ganglion its connexion by a commissure with its fellow would be an abnormality, and the olfactory ganglion in the lamellibranch would innervate the gills, adductor muscle, mantle, and rectum, parts which in gastropods are innervated from the visceral ganglia. The heart and pericardial chamber in the oyster lie along the anterior face of the adductor muscle, almost perpendicular to the direction of the gills, with which in Anodon they are parallel. In Anodon and the majority of lamelli- braiuhs the ventricle surrounds the intestine ; in the oyster the two are quite independent, the intestine pass ing above the pericardium. The renal organs of the oyster were discovered by Hoek to agree in their mor phological relations with those of other lamellibranchs.