Page:The New International Encyclopædia 1st ed. v. 14.djvu/839

OBESITY. |13 OBJECT TEACHING. duction of obesity three {jreat causes are active as a rule. These arc heredity, overindulfjenee in food and drinlc, and lack of exercise. Most persons over forty eat too much and e.xei'cise too little. Alcohol tends to fatten by substituting itself for food in the oxidizinj; process. Fat when once deposited favors the deposition of more fat, for by acting as a non-conducting envelope to the body it prevents the radiation of heat, and so decreases the conilnistion of those substances which, when not used to produce heat, are stored up as fat. The immediate cause of obesity is generally a faulty assimilation due to some digestive derangement by which oxidation of the albimiinous elements of the food is interfered with. The carbohydrates are not as was long thought directly to blame, since the}' are readily converted into carbon dioxide and water. On account, however, of the ease with which the carbohydrates are oxidized, the albuminous ele- ments of the food undergo incomplete oxidation, are not so fully decomposed, and the fat is in reality derived from them. The fatty portions of the food are not so prone to cause undue deposition of fat as are the carbohydrates, since they interfere less with the conversion of the nitrogenous elements, and ai-e less easily oxi- dized. The symptoms which may attend extreme de- grees of corpulence are a falling off of mental and physical activity, shortness of breath on the least exertion, and impairment of the functions of respiration, circulation, and digestion, together with anipmia and muscular weakness. This, however, is an extreme picture. It is a matter of daily observation that obesity is compatible with a high degree of mental and physical alert- ness and general good health. JIany plans of treatment, based on systems of exercise and diet, have been advocated for the reduction of fat, the mo-t notable being those of Banting, Ebstein, and Oertel. All of these systems have for their object the regulation of exercise in such a way that oxidation may pro- ceed in a normal manner, and regulation of the diet so that a less quantity than normal of the fat-producing elements is taken in. This object is attained in various ways. In the method of Banting the total (piantity of food is reduced, the liquids restricted, and the fats and carbohy- drates excluded. El)stein's method permits the use of fats, but eliminates the carbohydrates. Oertel's system is especially intended for in- dividuals with cardiac complications, and con- sists of three parts. First, the reduction of liquids with promotion, by baths or other means, of perspiration : second, restriction of the diet largely to proteid substances; and third, the taking of graduated exercises in walking up hill. Cathell proposed some years ago a method which was entirely independent of diet and exercise. This was the taking, on alternate days, of Kis- singen and Vicliy mineral waters, with the addi- tion, in obstinate eases, of lemon juice to the Kissingen, and aromatic ammonia to the Vichy. Thyroid extract enjoyed for a time a reputation as a fat-reducer, but its tendency to interference with the heart, which is apt to be weak in obese persons, makes it a somewhat dangerous drug. Among other substances which have been used for this purpose are iodine, bromine, mercury, lead, arsenic, lemon juice, sour wines, vinegar, Phytolacca, Gulf weed, and bladder wrack. -Many of these, while having an influence on the fat, act as slow poisons and damage the assimilative organs, so that their ultimate effect is injurious. OBI, o1)e, or OB. The westernmost of the great rivers of Siberia (Map: Asia. (! 2). It rises in the Altai Mountains, and Hows north- west, then north through the Siberian govern- ments of Tomsk and Tobolsk, emptying into the Arctic Ocean through an immense estuary, the Gulf of Obi, which is GOO miles long and (io miles in average width. The length of the river itself above the estuary is about 2.500 miles, and it is nearly two miles wide at its mouth, .fter emerging from the foot-hills of the Altai range the river flows for the remainder of its course through an almost perfectly level country con- sisting first of sandy steppes, then of rich tracts of fertile soil, and finally of vast marshes. In its lower course it divides repeatedly into paral- lel arms connected by cross-channels, forming a network of islands, which during floods are submerged under sheets of water many miles wide. Although not yet extensively xised as a waterway, the Obi with its tributaries presents a total navigable lengtli of over 9000 miles. In summer the main river and all its larger tribu- taries are navigable almost to their sources, and during the spring floods many secondary- tributaries can be ascended by light-draught steamers. The river is ice-bound near its mouth from October to June. Of its numerous tribu- taries the largest is the Irtysh (q.v. ), which is considerably longer than the main stream from the point of confluence. OBIS'PO (Sp., bishop). A Cub.an name of the spotted stingray (Aetohatus narinari). It is one of the eagle-rays, and is brown in color, with small, round, pale spots. O'BIT (OF. ohit, from Lat. ohitus. death, approach, from ohire, to meet, from o^, toward -j- ire, to go). Literally, the decease of an in- dividual. But as a certain ecclesiastical service was fixed to be celebrated on the day of death (in die ohiius) , the name can be applied to the service itself. Obit therefore signifies, in old Church language, the service performed for the departed. It consisted, in the Roman Church, of matins and lauds, followed by a mass for the dead. OBITER DICTUM. See Dictum. OBJECT-GLASS. The lens in a telescope (q.v.) or microscoije (q.v.), which is placed at the end of the tube nearest the object, and first receives the rays of light. Its function is to produce a real image of the object, and it is generally an achromatic lens. OBJECT TEACHING. mode of teaching in which objects are made the studies of young pupils. By this method a systematic attempt is made to exercise and train the senses of the child. Comenius (q.v.) in the (Irrnt Didiictir writes: "Let the senses be applied to the subject as often as possible, e.g. let hearing be joined with vision and the hand with speech. It is nof enough to apply to the ears, but the teacher nuist present to the eyes, that through them instruction may reach the imagination. Leave nothing till it has been impressed l).v means of the ear, the eye. the tongue, the hand," His Orhis Piciiis was the first school-book in which pictures were used to illustrate the various topics. In the work of