HOM 



HOR 



nodenns, commonly termed, from their 

 general shape and appearance, " sea- 

 cucumbers." See Echinodermata. 



HOMBERG'S PHOSPHORUS. Ig- 

 nited muriate of lime. See Phosphorus. 



HOMBERG'S PYROPHORUS {ttvp, 

 fire, (^ep&), to bring). A mixture of alum 

 and brown sugar, which takes fire on 

 exposure to the air. A more convenient 

 mixture is made with three parts of lamp- 

 black, four of burnt alum, and eight of 

 carbonate of potash. 



HOMBERG'S SEDATIVE SALT. 

 A name for boracic acid, which appears, 

 however, to possess no sedative property. 



HO'MO- (ojLiof , one and the same). A 

 Greek term, in composition denoting 

 resemblance, and thus distinguished from 

 the term hetero-, which denotes differ- 

 ence : — 



1. Homo-centric {Kevrpov, a centre). 

 Having the same centre, or being con- 

 centric. 



2. Homo-cereal (Kfp/co?, the tail of a 

 beast). A term applied to those fishes 

 which have tails with rays regularly di- 

 verging from the end of the backbone, 

 like the tail of a herring or trout. See 

 Hetero-cercal. 



3. Homo-dromal (5p6/iop, a course). A 

 terra recently suggested, in Botany, to 

 characterize the peduncles of the cyme 

 of monocotyledons, in which the direc- 

 tion of the spire is the same as that of 

 the central stem, and as distinguished 

 from the anti-dromal direction, which is 

 the reverse of that of the central stem. 



4. Homo-gamous {yd/jiof, marriage). A 

 term applied, in Botany, to those capi- 

 tula, in which all the flowers are herma- 

 phrodite. 



5. Homo-gangliata (7077X^0^, a nerve- 

 knot). A term applied by Owen to Cu- 

 vier's grand division Articulata of the 

 animal world ; the beings constituting 

 this division having a ganglionic nervous 

 system, and the ganglions symmetrically 

 arranged. They correspond with the an- 

 nulosa of Macleay, and the Diploneura 

 of Grant. See Hetero-gangliata. 



6. Homo-geneous (761/09, kind). A term 

 applied to substances consisting of similar 

 parts and properties, as distinguished 

 from hetero-geneous substances. Thus, 

 in minerals, sandstone is a homogene- 

 ous, granite a heterogeneous substance. 



7. Homo-logons (\6yof, a ratio). Having 

 the same ratio or proportion. Equiangu- 

 lar triangles, having sides containing cor- 

 responding equal angles proportional, are 

 said to be similar, and the corresponding 



166 



sides are homo-logous, i. e. having the 

 same ratio. Similar magnitudes, occu- 

 pying different places in a proportion, one 

 being an extreme, the other a mean, are 

 said to be homo-logous. 



8. Homo-logue {\6yo^, a description). 

 The same organ in different animals 

 under every variety of form and function. 



9. Homo-morphous {fxop(pr], form). Of 

 similar form ; a term proposed by Mr. 

 Westwood for certain neuropterous in- 

 sects, which, in their larva state, are 

 similar in form to the perfect insect, 

 though wingless, 



10. Homo-phonous {^usvr], a sound or 

 voice). A term applied, in Music, to two 

 or more sounds which are exactly of the 

 same pitch. In language the term is 

 applied to words or syllables which have 

 the same sound, though they are ex- 

 pressed in writing by various combina- 

 tions of letters. 



11. Homo-ptera (Trrepov, awing). An 

 order of insects in which the four wings 

 are of the same consistence, all of them 

 being composed of a firm membrane, as 

 in the lantern-fiy. 



12. Hom-organa {opyavov, an organ). 

 One of the primary classes of plants, as 

 divided with reference to their Rotation, 

 or general motion of the sap. See Heter- 

 organa. 



13. JTomo-frojjaZ (rpeTTO), to turn). Hav- 

 ing the same direction as the body to 

 which it belongs, but not being straight, 

 as applied, in botany, to the embryo of a 

 seed. 



HONET-DEW. A sweetish substance 

 ejected by very small homopterous in- 

 sects, called aphides, upon the leaves of 

 plants, and vulgarly supposed to be 

 caused by a blight, or some disease in the 

 plant. There is another kind of honey- 

 dew, observed only at particular times, 

 and in certain states of the atmosphere, 

 hanging occasionally in drops from the 

 points of the leaves of plants ; its cause 

 is not known. 



HONEY-STONE. Mellite. Mellitate 

 of alumina ; a mineral of a honey-yellow 

 colour, found situated on bituminous 

 wood and earth coal, and usually asso- 

 ciated with sulphur. 



HO'RARY {hora, an hour). This term, 

 as u^fedin astronomy, denotes the 

 which a C<>iigstial body descriji0»-tn one 

 hour, or the angle whicU-'lliat arc sub- 

 tends at the eye^'^i^Dtfiie spectator: the 

 horary motion ^ a "^iclestial body is 

 therefore \^i»fox the twenty-fourth part 



of a circled 





