A BR 



ABS 



in consequence of which the image of the 

 object, viewed through a lens, will be 

 surrounded by prismatic colours. Sphe- 

 rical aberration produces distortion, chro- 

 matic aberration produces false colour, of 

 the object. 



3. Aberration, circle of. The circle oi 

 coloured light observed, in experiments 

 with convex lenses, between the point 

 where the "violet or most refrangible, and 

 ihe point where the red or least refran- 

 gible rays meet. 



ABIETI'NJL {abies, a fir-tree). A sec- 

 tion of the Coniferas, or Fir-tree tribe of 

 plants, comprising the Fir, the Pine, the 

 Araucaria, the Dammara, and the Cun- 

 ninghamia. 



A'BLATIVE CASE {ab, from, fero, 

 latus, to take). Literally, the taking 

 away case ; a case belonging to the Latin 

 language, and known by prepositions, 

 expressed or understood. It is repre- 

 sented in the English language by the 

 preposition from. See Case. 



ABNO'RMAL {ab, from, norma, a rule). 

 Irregular ; that which deviates from the 

 usual order. The term anormal is also 

 employed to denote any thing that is 

 without rule or order. The terras are 

 nearly synonymous. 



ABO'RTIVE {aborior, to be born before 

 the time). A term applied in botany to 

 any part of a plant which does not ac- 

 quire its normal development: stamens 

 which have no anthers, and seeds which 

 have no embryos, are said to be abortive. 

 But abortion may be constant : the ova- 

 rium of the Cocoa palm is three-celled ; 

 the fruit has only one cell, the other two 

 becoming constantly abortive. 



ABRA'NCHIA(apriv.,/3pa'yx'a» gills). 

 The third order of the Anellida of Cuvier, 

 comprising animals which have no gills, 

 or apparent external organs of respira- 

 tion, but respire by the entire surface of 

 the skin, or by internal cavities. They 

 are distinguished into the setigerous, or 

 worms, and the non-setigerous, or leeches. 

 The term Abranchia has been also ap- 

 plied to an order of amphibious animals, 

 which are not known to undergo meta- 

 morphosis, but breathe by lungs during 

 the whole period of life. The order 

 comprises only two genera, viz. the me- 

 nopoma and the amphiuma of North 

 America. 



A'BRAZITE. A mineral found in the 

 cavities of volcanic rocks, with calcareous 

 spar, at Capo di Bove, near Rome. It 

 occurs in semi-globular masses, and in 

 octohedral crystals with a square base. 

 2 



It is also termed zeagonite and gismon" 

 dine. 



ABRUTTLY PINNATE. A pinnate 

 leaf is thus named in botany, when its 

 petiole has no terminal leaflet or tendril, 

 as in Orobus tuberosus. 



ABSCI'SSA {abscindo, to cut off). Linea 

 abscissa. A term employed in Conic Sec- 

 tions, to denote that portion of the major 

 axis of an ellipse which is cut off by an 

 ordinate. The term is equally applicable 

 to the parabola and to the hyperbola. See 

 Ordinate and Co-ordinuip. 



A'BSOLUTE and RE'LATIVE. In 

 logic, a noun which denotes an object 

 considered as a whole, and without re- 

 ference to any thing of which it is a part, 

 or to any other part distinguished from 

 it, is called absolute. When, on the other 

 hand, an object is considered as a part of 

 a whole, viewed in reference to the 

 whole, or to another part of a more com- 

 plex object of thought, the noun express- 

 ing this view is called relative. Thus, 

 " father " and " son " are relatives, being 

 regarded, each as a part of the complex 

 object, father-and son ; whereas the 

 same object designated absolutely would 

 be termed a man, living being, &c. 



ABSORPTION {absorbeo, to suck up). 

 A function in physiology, by which the 

 materials of growth are absorbed and con- 

 veyed to the organs of the body, and by 

 which the decayed and useless parts are 

 absorbed and removed from the system. 



1. Interstitial Absorption. The func- 

 tion by which the particles of the tissue 

 which fill the meshes of the capillary net- 

 work are removed, as in the atrophy of 

 the tail of the tadpole, and of the pupil- 

 lary membrane in the foetus, and in the 

 development of cells in bones. 



2. Absorption, in Chemistry. This term 

 denotes the passage of a gas or vapour 

 into a liquid or solid substance ; or that of 

 a liquid into the pore*, of a solid. Thus, 

 water absorbs carbonic acid gas, lime 

 absorbs water, &c. 



ABSTRACT and CONCRETE. L In 

 logic, when a notion derived from the 

 view taken of any object, is expressed 

 with a reference to, or as taken in con- 

 junction with, the object which furnished 

 the notion, it is expressed by a concrete 

 term, as "foolish" or "fool;" when 

 without any such reference, by an abs- 

 tract term, as " folly." 2. in arithmetic, 

 when numbers are used with reference 

 to the things numbered, as 3 shillings, 4 

 acres, 5 kingdoms, they are said to be con- 

 crete numbers ; when used without such 



