ARC. 



22 



ARM- 



archigony (arkig'onl) n. [Gk. archi, 

 first ; gonos, offspring.] The first 

 origin of life by spontaneous genera- 

 tion (bio!.}. 



archinephric (ar'kmef'rik) a. [Gk. 

 archi, first ; nephros, kidney.] Appl. 

 the duct into which the pronephric 

 tubules open (emb.}. 



archinephros (ar'kinef'ros) n. [Gk. 

 archi, first ; nephros, kidney.] The 

 primitive kidney (emb.}. 



archipallium (ar'kTpal'ium) n. [Gk. 

 archi, first ; L. pallium, a mantle.] 

 The olfactory region of the cerebral 

 hemispheres (phys.}. 



archipterygium (ar'kipterij'ium) n. 

 [Gk. archi, first ; pterygion, little 

 wing.] Type of fin in which the 

 skeleton consists of an elongated 

 segmented central axis and two 

 rows of jointed rays (zool.}. 



architype (ar'kitip) n. [Gk. archi, 

 first ; typos, type.] An original type 

 from which others may be derived 

 (biol.}. 



archoplasm (ar'koplazm) n. [Gk. 

 archon, ruler ; plasma, something 

 moulded.] The substance con- 

 stituting the attraction sphere, 

 astral rays, and spindle-fibres 

 (emb.}. 



arclcentrous (ar'kisen'trus) a. [L. 

 arcus, bow ; centrum, centre.] 

 Appl. vertebral columns in which 

 the centra are mainly derived from 

 the arch tissue (emb., anat.). 



arciferous (arsif'eYus) a. [L. arcus, 

 bow ; ferre, to carry.] Appl. pec- 

 toral arch of toads, etc., where the 

 precoracoid and coracoid are widely 

 separated and connected by a large 

 arched epicoracoid (zool.}. 



arciform (ar'siform) a. [L. arcus, 

 bow ; forma, shape.] Shaped like 

 an arch or bow (zool.}. 



arcocentrous (ar'kb'sen'trus) a. [L. 

 arcus, bow ; centrum, centre.] Appl. 

 vertebral columns with inconspicu- 

 ous chordal sheath and centra de- 

 rived from arch tissue (zool.}. 



arcocentrum (ar'kosSn'trum) n. [L. 

 arcus, bow ; centrum, centre.] A 

 centrum formed from parts of neural 

 and haemal arches (zool.}. 



arcualia (ar'kua'lia) n.plu. [L. arcus, 

 bow.] Small cartilaginous pieces, 

 dorsal and ventral, fused or free, on 



the vertebral column of fishes 

 (zool.}. 



arcuate (ar'kuat) a. [L. arcus, bow.] 

 Curved or shaped like a bow. 



ardellae (ardeTe) n. plu. [Gk. ardein, 

 to sprinkle.] Small apothecia of 

 certain lichens having the appear- 

 ance of dust (bot.}. 



area (a'rea) n. [L. area, ground-space.] 

 A surface, as area opaca, area 

 vasculosa (smb.}. 



arenaceous (arSna'shus) a. [L. arena, 

 sand.] Having the properties or 

 appearance of sand ; sandy. 



areola (are'ola) n. [L. areola, dim. of 

 area, space.] A small coloured 

 circle round a nipple ; the part of 

 the iris bordering the pupil of the 

 eye (anat.} ; one of the small spaces 

 or interstices of a special kind of 

 tissue (zool.} ; the areas defined by 

 cracks on the surface of lichens (bot.}. 



areolar (are'olar), areolate (are'olat) a. 

 [L. areola, space.] Of or like an 

 areola, having distinct spaces or 

 interstices (bot.} ; areolar is appl. a 

 kind of connective tissue with the 

 fibres loosely attached (zool.}. 



argenteal (arjen'teal) a._ [L. argenteus, 

 silvern.] Appl. layer of the eye 

 containing calcic crystals (zvol.}. 



argenteous (arjen'teus) a. [L. argen- 

 teus, silvern.] Like silver (bot.}. 



argent euin (arjgn'teum) n. [L. argen- 

 tum, silver.] A dermal reflecting 

 tissue layer of iridocytes without 

 chromatophores in fishes (zool.}. 



aril (ar'il), arillus (aril'us) n. [F. 

 arille, Sp. arillo, a small hoop.] 

 An additional investment formed on 

 a seed after fertilization (bot.}. 



arillode (ar'ilod) n. [F. arille, hoop ; 

 Gk. eidos, like.] A false arillus 

 arising from the micropyle as an 

 expansion of the exostome (bot.}. 



arista (arls'ta) n. [L. arista, beard of 

 an ear of corn.] Awn ; long-pointed 

 process as in many grasses (bot.} ; 

 a bristle borne by the antenna of 

 many brachycerous Diptera (zool.}. 



Aristotle's lantern (Ar'istot'lz), the 

 masticating apparatus of the sea- 

 urchin (zool.}. 



armature (ar'matur) n. [L. arma, 

 weapons.] Anything which serves 

 to defend, as hairs, prickles, thorns 

 (bot.} ; spines, stings, etc. (zool.}. 



