D I C 



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I G 



granular limestone, and thus named from 

 possessing two prominent spiral umbones, 

 which resemble two twisted horns. 

 DICHO'TOMOUS. (from ^t'xaandrl/ivw. Gr. 

 dichotome, Fr. dicotomo, It.) Forked ; 

 regularly and continually divided by 

 pairs from the top to the bottom : ap- 

 plied to stems dividing into two parts ; 

 example, the misletoe. 



DI'CHROIT. ) A mineral, called also io- 

 DI'CHROITE. ) lite. The prismatic quartz 

 of Mohs ; iolithe of Haiiy. Dichroite is 

 of a blue colour, shining lustre, and con- 

 choidal fracture. It consists of nearly 

 50 per cent, of silica, alumina 30, magne- 

 sia 11, oxide of iron 5, with a trace of 

 oxide of manganese. It occurs in granite 

 and gneiss. 



Dico'ccous. (from die and KOKKOZ, Gr.) 

 A capsule which consists of two cohering 

 grains, or cells, with one seed in each. 

 DJCOTYLE'DON. (from dig andjcoruX/;o*'.) 

 A plant which has two cotyledons or se- 

 minal leaves. 



DICOTYLE'DONOUS. Every plant the em- 

 bryo of whose seed is made up of two lobes, 

 or which possesses two cotyledons, or semi- 

 nal leaves, is included in this great division 

 of the vegetable kingdom ; or is a dico- 

 tyledonous plant. The stems of dico- 

 tyledonous plants are all exogenous, that 

 is, they increase externally by the addi- 

 tion of concentric layers from without ; 

 these concentric additions being made 

 annually, a vertical section of a tree of 

 this division will shew, at once, its age ; 

 the number of rings or circles marking 

 its number of years. Dicotyledonous 

 plants may always be distinguished from 

 monocotyledonous by their leaves : mo- 

 nocotyledonous plants have the veins of 

 their leaves parallel and not reticulated, 

 while all dicotyledonous plants have the 

 veins of their leaves reticulated. 

 DIDA'CTYLE. (diSuKTvXog, Gr.) An ani- 

 mal having two toes only. 

 DIDA'CTYLOUS. Two-toed ; having two 



toes only. 



DIDE'LPHIS. > (from dig and Setyvg, Gr. 

 DIDE'LPHYS. $ having two wombs.) A 

 genus of animals, belonging to the class 

 Mammalia, order Ferae. All the animals 

 of this genus are marsupial, that is, pos- 

 sess an external abdominal pouch, mar- 

 supium, or sac, in which the foetus is 

 placed after a very short period of uter- 

 ine gestation, and where it remains sus- 

 pended to the nipple by its mouth, until 

 sufficiently matured to come forth to the 

 external air. The opossum and kangaroo 

 are examples. The didelphys affords the 

 only known example of mammalian re- 

 mains in the secondary formations. 

 DIPE'LPHOID. Belonging to the genus di- 

 delphys. 



DIDYNA'MIA. (from cJeand dvvafiig, Gr.) 

 The name given to the 14th class in Lin- 

 nseus's artificial arrangement : it has four 

 stamens, two long and two short. This class 

 is easily distinguishable from the 4th class, 

 Tetrandria, which has also four stamens. 

 The flowers of this class are generally la- 

 biate ; corolla monopetalous. It is di- 

 vided into two orders: Gymnospermia, 

 with four naked seeds in the bottom of 

 the calyx, and Augiospermia, the seeds 

 numerous and contained in a seed-vessel. 

 In the first order, with the naked seeds, 

 the plants are mostly aromatic and whole- 

 some, including the mint, lavender, &c. 

 In the second, where the seeds are con- 

 tained in a seed-vessel, we find digitalis, 

 and other poisonous plants. 

 DIDYNA'MIC. ) Belonging to the class 

 DIDYNA'MOUS. ) Didynamia. Plants hav- 

 ing four stamens, two of which are 

 shorter than the others, are called didy- 

 namous. 



DI'FFLUENT. } (diffluens, Lat.) The 

 DI'FFLUENCY. \ quality of flowing 

 away on all sides, as does water; the 

 effect of fluidity. 



DI'FFLUENT. Flowing every way ; not fixed. 

 Water is diffluent, but if it be converted into 

 ice it ceases to be so, becoming fixed. 

 DIFFU'SE. (from diffundo, Lat.) To 



pour out ; to spread ; to disperse. 

 DIFFU'SE. ( (diffus, Fr. diffuso, It.) 

 DIFFU'SED. S Poured out ; scattered ; 

 spread. Widely spread out ; scattered ; 

 dispersed. 



DIFFU'SEDLY. (diffustment , Fr. diffusa- 

 mente, It. diffuse, Lat.,) In a scattered 

 manner. 

 DIFFU'SEDNESS. The state of being widely 



spread out, of being scattered. 

 DIFFU'SIVE. Having the quality of spread- 

 ing in all directions, as water. 

 DIGA'STRIC. (from dig and yaor?}p, Gr.) 



Having two bellies. 



DI'GITAGRADA. In Cuvier's arrangement, 

 the second tribe of carnivora. The name 

 digitagrada has been applied to them 

 from the circumstance of the animals 

 which compose this tribe walking on the 

 ends of their toes. 



DI'GITATE. ) (digitatus, Lat.) A sort of 

 DI'GITATED. $ compound leaf, composed 

 of two or more leaflets. Botanists in- 

 clude under the name digitate, binate and 

 ternate leaves, as well as those having 

 more than five leaflets, as the horse-ches- 

 nut, which has seven leaflets. 

 DIGY'JSIA. (from jg and yvvfj, Gr.) The 

 second order in Linnseus's artificial sys- 

 tem, comprehending such plants as have 

 two styles, or pistils. 



DIGY'NIAN. ) Having two styles, or pis- 

 DJGY'NIOUS. $ tils; belonging to the 

 order Digynia. 



