236 MANUAL OF BOTANY 



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number of projections from its walls. Other examples of the 

 formation of spurious dissepiments producing changes in the 

 ovary have been already mentioned. 



2nd. Other alterations are produced by the abortion or ob- 

 literation of parts, as the ovary ripens. Thus the young ovary 

 of the Oak consists of three cells, each of which contains 

 two ovules, but the fruit has only one cell and one seed, so that 

 in the course of development five ovules and two cells have 

 become obliterated. In the Birch we have an ovary with two 

 cells, containing one ovule in each, but the fruit is one-celled 

 and one-seeded, so that here one cell and one ovule have become 

 obliterated. In the Ash, Horseehestnut, Elm, and many other 

 plants, similar changes are produced in the matured ovary by 

 the abortion or obliteration of certain parts. 



3rd. Changes are frequently caused in the ovary from a 

 great development of succulent parenchyma. This is associated 

 also with changes in the contents of the cells of the parenchyma, 

 which become charged with sugar, vegetable acids, and various 

 flavouring matters, giving its peculiar character to each fruit. 

 The pulp of the Guava, Gooseberry, Tomato, and some other 

 fruits, in which the seeds are imbedded, appears to be produced 

 from the placentas ; and that of the Orange is of a similar 

 nature. 



Although the fruit may thus be described as consisting 

 essentially of the ovary or ovaries, modified in the directions 

 described, other parts of the flower are also frequently present, 

 and enter into its composition. Thus, in those cases where 

 the calyx or receptacular tube is adherent to the ovary, as in 

 the Apple, Quince {fig. 299), Pear, Melon, and Gooseberry, it 

 necessarily forms a part of the fruit ; in the Eose the concave 

 thalamus (fig. 285, r, r), which bears the carpels on its inner 

 surface, becomes a portion of the fruit ; in the Strawberry (fig. 

 505), the fruit consists of the succulent hemispherical thalamus, 

 bearing the carpels on its convex surface ; in the Acorn (fig. 

 198), Hazel-nut (fig. 199), and Filbert, it consists of pistil 

 and bracts, combined together; while in the Pineapple (fig. 

 167), it is formed of the ovaries, floral envelopes, and bracts 

 of several flowers ; in the Fig also (fig. 204) we have a fruit 

 produced by a number of separate flowers enclosed in a hollow 

 fleshy receptacle. These examples, and a number of others 

 which might be alluded to, wiU show, that although the fruit 

 consists essentially of the modified ovary or ovaries, enclosing 

 the seeds which are developed from the ovules after fertOisation 



