ORGANS OF EEPEODUCTION. 



319 



Fig. 712. 



terms are applied to the seed in the same sense as to the ovule. 

 The ovule has been compared to a bud, and has been called the 

 seed-bud by Schleiden and others. 



The ovule is in most cases enclosed in the cavity of the ovary ; 

 but all plants of the Coniferse, Cycadacese, and allied orders are 

 exceptions to this ; thus in the Cycadacese, the ovules are 

 situated on the margins of leaves in a peculiarly metamorphosed 

 condition, and in the Coniferse, at the base of indurated bracts or 

 open carpellary leaves (/^. 1\'2,ov). In these eases, as there is no 

 proper ovary, there is no style or stigma, 

 and the ovules therefore, instead of being 

 fertilized by pollen applied through the 

 stigma, as is commonly the case, are ex- 

 posed and fertilized by its direct appli- 

 cation. Such ovules are therefore termed 

 naked. The seeds of such plants are also 

 necessarily naked, and hence such plants 

 have been called Gymnospermous Hants, 

 — that is, plants with naked seeds ; 

 while those plants in which the ovules 

 and seeds are distinctly enclosed in an 

 ovary, have been called Angiospermous 

 Plants. It should be noticed, however, 

 that there are some plants in which the -f^- J12. Bract or carpeiiary 



J , ,.^„ 1 J • ^1 leaf, sc, of a species of Piwjts, 



seeds become partially naked m the bearing two naked ovules, 

 course of development, as in the Mig- £:"',,^L'tL^^^^ i mic, micro- 



/ r ^ c 1 \ T J • ry 1 PJ^'^ °^ ^^^ ovule, 



nonette (Jig. 651), Leontice, Cuphea, 



&c., in which cases they are sometimes termed seminude. True 

 Gymnospermous Plants, or those in which the ovules are naked 

 from their earliest formation, should be carefully distinguished 

 from those with seminude ovules, as the former character is 

 always associated with important structural and physiological 

 peculiarities in the plants themselves, as abeady noticed in 

 treating of the stem and some other parts. 



Number and position of the Ovules. — The number of 

 ovules in the ovary, or in each of its cells, varies. Thus in the 

 Polygonacese {fig. 713), Compositse, Thymelaeese, Dipsacaceae, 

 &c., the ovary contains but a solitary ovule ; in the Umbelliferae, 

 Araliacese, &c., there is but one ovide in each cell. "When there 

 is more than one ovule in the ovary, or in each of its cells, the 

 number may be either uniform and easily counted, when the 

 ovules are said to be definite, as in Mscidus {fig. 717), — and the 

 ovary or cell is then described as biovidate, triovidate, quadri- 

 ovulate, qxdnqueovulate, &c., — or, the ovules may be very nu- 

 merous, when the ovary or cell is said to be midtiovulate or 

 indefinite, as in Viola {fig. 427). 



The position of the ovules with regard to the cavity in which 

 they are placed is also liable to vary. Thus when there is 



