216 



MANUAL OF BOTANY 



the orthotropous and anatropous forms ; to it the term amphi- 

 tropous has been applied. In this ovule, which is also called 

 heterotropoits or transverse, the hilum, /, is on one side, and 

 the micropyle, in, and chalaza, ch, are placed transversely to it 

 (fig. 474), and therefore parallel to the placenta. In this case 

 the hilum is connected to the chalaza by a short raphe, r. 



The ovules of Angiospermons plants are enclosed in an ovary 

 (fig- 436). Those of the Gymnosperms, including the Coniferne, 

 Cycadacese, and allied orders, are always exposed without this 

 case. In Cycas they are situated on the margins of peculiarly 

 metamorphosed leaves ; in the Coniferse they are formed at 

 the bases of indurated bracts or scales (fig. 475); in Taxusthey 

 are borne at the ends of certain branches. In some Angio- 



FlG. 473. 



FiCt. 474. 



Fkl. 47;i, Vertical section of the an.atroyjous ovule of the Dandelion. 

 A. Hilum. /. Micropyle or foramen, w. Nuce'lus. .s. Base of the nucellus. 



c/i. Olialaza. ?-. Eaphe. Fig. 474. Longiturlinal section of the amphi- 



tropous or transverse ovale of Lemna tristdca. f. Funiculus, n. Nueellus. 

 p. Primine, aee. Secundine. .s. Embryo-sae. ch. Ohalaza. r. Raphe. 

 m. Micropyle. From Schleideo, 



sperms the seeds become partially exposed in the course of the 

 development of the ovary with the fruit, the apex of the ovary 

 opening and disclosing them in its cavity. This takes place in 

 the Mignonette (fig. 509), Leontice, and Ouphea. These must 

 not be confused with Gymnospermous plants, in which the 

 ovules are naked from their first formation. 



Number and Position of the Ovules. — a. Number. — The 

 number of ovules in the ovary, or in each of its cells, varies in 

 different plants. In the Polygonaceas, Composita?, Thyme- 

 lacese, and Dipsaoese, the ovary contains but a solitary ovule ; 

 in the Umbelliferse and Araliacese, there is but one ovule in 

 each cell. When there is more than one ovule in the ovary, 

 or in each of its cells, the number may be either few and 



