ITS STRUCTURE AND TRANSFORMATIONS. 309 



a fig, and a pine-ai^ple consist of the ripened products of many 

 flowers, crowded on an axis or common receptacle, which makes a 

 part of the edible mass. 



585. Under the general name of fruit, therefore, even as the word 

 is used by the botanists, things of very different structure or of dif- 

 ferent degrees of complexity are confounded. We must distinguish, 

 therefore, betAveen simple fruits, resulting from a single flower, and 

 a multiple fruit, resulting from the parts of more than one flower 

 combined or collected into a mass. "We must also distinguish be- 

 tween true fruits, formed of a matui-ed pistil, either alone or with a 

 calyx, &c. adnate to it, and fruits, so called, of which the pericarp 

 does not form an essential part. 



586. Obliteration or Alteration. The pericarp, being merely the 

 pistil matured, should accord in structure with the latter, and con- 

 tain no organs or parts that do not exist in the fertilized ovary. 

 Some alterations, however, often take place during the growth of 

 the fruit, in consequence of the abortion or obliteration of parts. 

 Thus, the ovary of the Oak consists of tliree cells, with a pair of 

 ovules in each ; but the acorn, or ripened fruit, presents a single 

 cell, filled with a solitary seed. In this case, only one ovule is 

 matured, and two cells and five ovules are suppressed. The ovary 

 of the Ilorsechestnut and Buckeye is similar in structure (Fig. 

 777 -780), and seldom ripens more than one or two seeds ; but the 

 abortive seeds and cells may be detected in the ripe fruit. The 

 ovary of the Birch and of the Elm is two-celled, with a single ovule 

 in each cell : the fruit is one-celled, with a solitary seed ; one of the 

 ovules or young seeds being uniformly abortive, while the other in 

 enlarging thrusts the dissepiment to one side, so as gradually to ob- 

 literate the empty cell ; and similar instances of suppression in the 

 fruit of parts actually extant in the ovary are not uncommon. On 

 the other hand, there are sometimes more cells in the fruit than 

 properly belong to the pistil. For instance, the ovary of Datura 

 Stramonium is two-celled ; but the fruit soon becomes spuriously 

 four-celled by a false partition connecting each placenta with the 

 dorsal suture. So the compound ovary of Flax when young is five- 

 celled, but with a strong projection from the back of each cell (Fig. 

 500) which at maturity divides the cell into two, thus rendering 

 the fruit ten-celled. And some legumes are divided transversely 

 into several cells, although the ovaiy was one-celled with a continu- 

 ous cavity in the flower. 



