OVA 



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not pass through the centre of its 

 longitudinal diameter, but lies 

 nearer to one end : egg-shaped. 



OVA'RIUM, ) (ovaire, Fr. ovaja, It.) 



O'VARY. ) That part of the body 

 which contains the ova, and in 

 which impregnation is performed. 

 In animals, it is only in the 

 organs termed ovaries, that ova are 

 formed. 



In botany, that part of the flower 

 which ripens into the fruit, and 

 contains the seed. 



O'VATE. (ovatus, made like an egg, 

 from ovum, Lat.) Of the shape of 

 an egg ; egg-shaped. 



OVIDTTCT. (from ovum, an egg, and 

 ductus, a passage, Lat.) A canal, 

 or duct, through which the ova 

 pass, after impregnation, from the 

 ovary to the uterus. In the human 

 subject the oviducts are called the 

 Fallopian tubes. 



O'VIFORM. (from ovum, an egg, and 

 forma, shape, Lat.) Of the form 

 or shape of an egg. 



OVI'PAROUS. (from ovum, an egg, and 

 pario, to produce, Lat. ovipare, Fr. 

 oviparo, It.) All animals which 

 lay eggs, enclosed in a calcareous 

 shell, are called oviparous. Ovi- 

 parous production is thus charac- 

 terized; the young animal is not 

 attached to the parieties of the ovi- 

 duct, but remains separated from it 

 by its external envelope ; its aliment 

 being enclosed in a sac, which 

 is attached to its intestinal 

 canal. 



OVO'-VIVIPAROUS. Producing young 

 in an egg, which is hatched inter- 

 nally, and previously to exclusion 

 by the parent. Some animals, 

 such as the salamander and the 

 viper, never lay their eggs, but 

 these are hatched within the body 

 of the parent; so that although 

 originally contained in eggs, the 

 offspring are brought forth in a 

 living state. Such animals are 

 termed ovo-viviparous. 



OVIPOSITOR, A name given to the 



terminal apex of the abdomen of 

 insects. 



O'VULE. } (dim. of ovum, an egg, 



O'VULUM. ) Lat.) In botany, the 

 seed before it is perfected. The 

 small bodies produced on the mar- 

 gins of the carpella in the pistil, 

 are called ovula, or ovules ; when 

 perfected, they become the seed of 

 the plant. The ovule is generally 

 attached to the placenta of the 

 ovarium by a very small stalk. 



OVULI'TES. A genus of foraminated 

 polypifers, said to be known only 

 as fossil, of minute size, not ex- 

 ceeding two millimetres in length. 

 Ovulites is a stony, free, oviform, 

 or c} 7 lindrical, polypifer ; hollow 

 within; the extremities generally 

 perforated, having minute pores 

 regularly diffused over the surface. 



O'XFORD CLAY. Called also ciunch clay. 

 A bed of dark blue clay, sometimes 

 nearly six hundred feet in thick- 

 ness, interposed between the lower 

 and the middle oolites. 



OXIDA'TION. That process by which 

 metals, and other substances, are 

 converted into oxides by their com- 

 bination with oxygen. 



O'XIDE. | A substance combined with 



O'XYDE. ) oxygen, without being in 

 the state of an acid. 



O'XIDIZED. Converted into an oxide, 

 by combination with oxygen. 



O'XYGEN. (from oi>9, acid, and 

 ryei/vau;, to produce, Gr.) So called 

 from its property of forming acids. 

 One of the simple or elementary 

 substances, and one of the five 

 which exist as gas. So generally 

 does oxygen enter into combination 

 with metallic and non- metallic 

 bodies, and in such large propor- 

 tions, that it has been computed 

 that one-half of the ponderable 

 matter of the globe is composed of 

 oxygen gas. Oxygen constitutes, 

 by measure, 21 per cent, by weight 

 23 per cent, of the volume of the 

 atmosphere ; it forms a third part, 

 by measure, of the gasses composing 



