USED IN NATURAL HISTORY. 



57 



inent crystals of nearly equal 

 size. 



DUCT. A canal, pipe, or conduit. 



DTTCT (Thoracic). The canal or 

 duct which conveys the chyle in- 

 to the blood. 



DUCTI'LITY. fr. lat. duco, to draw. 

 That property of bodies by which 

 they admit of being drawn out 

 into wire. 



DUCTOR Lat. A leader. 



DULCAMA'RA. fr. lat. dulcis, sweet ; 

 amnra, bitter. Bitter-sweet. Sys- 

 tematic name of a genus of 

 plants. 



DU'MOSE. fr. lat. dumus, a bush 

 or bramble. Applied to shrubs 

 which are low and much branch- 

 ed. 



DUXES. Fr. Downs. Low hills of 

 blown sand. (p. 124, Book viii). 



DUPLICATED. Divided into plaits 

 or folds. 



DUPLICATUHE. A fold; any thing 

 doubled. 



DUPLO fr. lat. duo, two-, plica, a 

 fold. Two-fold. A prefix deno- 

 ting double the number or size. 



DURA. Lat. Hard. Dura mater is 

 a dense membrane, which covers 

 the brain, lying between it and 

 the skull. 



DURA'MEN. Lat. A hardening. 

 Systematic name of heart-wood. 



DUVALII. Lat. OfDuval. 



DYKE or DIKE. A provincial name 

 for wall. A geological term ap- 

 plied to a mass of igneous or un- 

 stratified rocks, when it appears 

 as if injected into a rent in the 

 stratih'ed rock, cutting across the 

 strata. A dyke differs from a vein, 

 in being larger, and in having par- 

 allel sides, (p. 118, Book viii). 



DYITA'MIC. fr. yr. dunamis, power, 

 force. Belonging or relating to 

 dynamics. 



DTXA'MICS. The doctrine of forces, 

 as exhibited in moving bodies 

 which are at liberty to obey the 

 impulses communicated to them. 

 The motions of celestial bodies in 



their orbits, or of a stone falling 

 freely through the air, are em- 

 braced in the study of dynamics. 



DYSTO'MIC. fr. gr. dus, difficulty; 

 temno, to cut. Difficult cleav- 

 age. 



DYTIS'CUS. fr. gr. dutikos, diving, 

 expert in diving. Name of a ge- 

 nus of aquatic insects. 



EARED. Applied to lobe-like pro- 

 cesses observed on certain leaves, 

 and on shells. 



EARTHS. Formerly chemists, be- 

 lieving them to be simple bodies, 

 included the following substances 

 under the name of earths : ba- 

 ryta, strontia, lime, magnesia, alu 

 mina or clay, silica, glucina, zir 

 coma, and yttria. Research has 

 shown that all have metallic or 

 metalloid bases; they are called 

 metallic oxides. Baryta, strontia, 

 lime, and magnesia are termed 

 alkaline earths. 



EARTHQUAKE. A sudden motion of 

 the solid surface of the globe, 

 probably occasioned by the same 

 causes as those which produce 

 volcanic eruptions, (p. 97, Book 

 viii). 



EBULLI'TIOW. The act of boiling. 



E'CDYSIS. fr. gr. ekdusis, the act of 

 stripping. Moulting of the skin. 



ECHELETTE. Fr. A little ladder. 

 Systematic name of the creepers. 



ECHE'KEIS. fr. gr. echo, I hold; na- 

 us, ship: a ship-holder, an anchor. 

 Systematic name of a family of 

 fishes, which the ancients sup- 

 posed were capable of arresting 

 the course of a vessel under sail. 



E'CHIMYS. fr. gr. echinos, spiny; 

 mus, a rat. A genus of mam- 

 mals; a sort of rat found in South 

 America. 



ECHI'DNA. fr. gr. A viper or snake. 

 The name of a monster, the up- 

 per part of whose body was in 

 the form of a beautiful woman, 

 and the lower part like that of a 

 hideous serpent. A genus of 



