Page:The New International Encyclopædia 1st ed. v. 17.djvu/682

SCALE INSECT. 614 SCALES OF NOTATION. suinyed upon ilonnnnt fruit trees. <.'enerall.v in the 'bripht 9unlit:ht, when ova|>oration will be so suee.lv that the trees will remain uninjured. Manv treatments of this kind have been suecess- ful. but others have resulted in the loss of valu- able trees. FLUTED 8CALE. a. full-grown feiimU> : h, same, after secretion ot Uuted egg-snc. Petroleum ond water mixed by spe- cially devised pumps has been etfective. A V ' mixture of unslaked lime (:iO pounds), sulphur (20 ]iouiuls), and salt ( 15 pminds) has been successful in California against armored scales, and in portions of the East also. The in- gredients are placed together in a barrel Avith thirty or forty gaUons of water and boiled with steam for three or four hours. The mix- ture should be diluted to sixty gallons and should preferably be applied hot. It leaves a limy coat- ing which acts as a deterrent to the young scales, and when not washed ciff by rains it retains its value for several weeks. Whale-oil or fish-oil soap, preferably Tuade with potash lye, is dissolved in water by boiling at the rate of two pounds of soap to a gallon of water, and iiiakes an excel- lent winter wash for armored scales. If applied hot and on a warm day in winter it can easily be put on trees with an ordinary spray pump. On a cold day, however, it will clog. Many of the States have passed laws to prevent the intro- duction of nursery stock unless accompanied by a certificate from a State official or a recognized expert that it has been inspected and found free from scale insects, or unless it has been fumi- gated with hydrocyanic acid gas. To perform this fumigation at a nursery a small air-tight fumigation house is usually constructed. See IN.SECTICIDE. Consult: Green, Coccidw of Ceylon (London, 1896-90) ; Comstock, Manual for the Htudy of Insects (Ithaca, 189,t): Howard, The Insect Book (Xew York, 1902) ; Cockerell, -'Tables for the Determination of the Genera of Coceidie," in the Caimdian Entomologist (London, Ont., 1899) ; llarlatt, Farmers' BuUetin No. 127, United »S7a?c.s Department of Agriculture (Wash- ington, 1901): Marlatt, Circular Jj2, second series ( ib., 1902). SCALES. Small plates arising from the skin and forming the covering or armature of the bodies of various animals, as fishes, lizards, snakes, and a few mammals. In fishes the,y are present in most forms as calcified plates in the skin, which may be so minute as to be almost microscopic, or in the form of large plates. Agassiz classified scales into placoid, ganoid, ctenoid, and cycloid, and classified fishes into these four groups. The most primitive scales, found in the elasmobranchs, consist of a basal plate of dentine bearing a central spine, covered externally by an enamel coat. The former is derived from the derma and the enamel is se- creted by the epidermis. These are the placoid scales, and they show a great similarity in their structure and development to teeth (q.v. ). In ganoid scales the basal portion is formed as in placoid scales and is covered by a coating of smooth, hard substance called ganoin. These are generally of a rhonilioid form, as in (he gar- pike (Lepidosteus) . Hoth ctenoid and cycloid scales ma.v occur within the same famil.v, or even smaller group, so that their lack of imjiortance as characters upon which to base a classification must be conceded. Among the Amphibia more or less calcified or ossified scales are entirely restricted to the Stegocephali and Apoda. Those of the former group (which is extinct) were small and partl.v calcified or perhaps ossified, "and we can only surmise," says tiadow, "that these scales were covered by corrcs|)on<ling dernial sheaths." The modern cseeilians luive a partial scale-ai'mature which consists of calcareous cell-secretions, and is consequently an entirely mesodermal product of the deeper layers of the cutis. ( See Molting.) Reptiles have from the earliest times been characterized by their coating of scales in most groups. The term in its ordinar.y sense, however, applies mainl.y to the covering of modern lizards and snakes. The scales of these creatures are formed by the cutis, and have a horny epidermal cover- ing, which peels off periodicall.v when the skin is 'shed.' In some lizards they are nearly absent; in many the.v contain 'osteoderms' or ossified por- tions of the cutis, over a part or all of the body. Snakes never have osteoderms. Well-developed scales overlap, but in some eases lie flat, edge to edge. In birds, where a serablanfe of scales appears, as in the penguins, they are to be accounted for as modified feathers; and in scaly mammals, such as the manis and the scale-tailed squirrel (Anomalurus) . the scales are formed of ag- glutinated hairs. SCALES OF NOTATION. Systems for writing numbers have Ijeen formed with various bases ; those known to have been used by civil- ized or semi-civilized peoples are chiefly the quinary (scale of 5), denary (scale of 10), duo- decimal (scale of 12), vicenary (scale of 20), and sexagesimal (scale of 60) systems. The binary system (scale of 2) was advocated by Leibnitz for scientific purposes. Such a system requires onlv the figures 0, 1. and reduces the fundamental operations to addition and subtrac- tion. But these advantages are offset by the ex- cessive repetitions of the digits to express ordi- nary numbers. Thus 289 is expressed in the binary scale 100.100,001. The ternary and quater- nary s,ystems, the latter of which is known to have been u.sed by certain savage tribes, are open to the same objection. The quinary system (scale of 5) probabl,y originated in the practice of finger reckoning. (See Finger SyMnoLiSM.) It is known to have been used by many savage tribes, especially among the primitive .South Americans and proliabl.v among the early Rus- sians. The senary .system (scale of G). septenary (scale of 7), octary (scale of 8), and nonary (scale of 9) may be said to exist in theory only. The denary scale as a system of numeration is practically • co-extensive with civilization. It, like the quinary scale, doubtless originated in the finger reckoning of primitive peoples. Thi.s system owes its popularit.v largely to the sim- plicity and power of the Hindu notation. The base 12 of the duodecimal scale may have been suggested b.y the twelve lunations in the solar year. Its popnlarity among the Romans is well attested, and the dozen, gross, shilling, foot, and