LESSON 20.] ITS KINDS. 127 



surface, and too small to be much noticed. And mulberries, figs, 

 and pine-apples are masses of many fruits with a pulpy flower-stalk, 

 &c. Passing these by for the present, let us now consider only 



335. Simple Fruits. These are such as are formed by the ripening 

 of a single pistil, whether simple (305) or compound (311). 



336. A simple fruit consists, then, of the Seed-vessel (technically 

 called the Pericarp}, or the walls of the ovary matured, and the seeds^ 

 contained in it. Its structure is generally the same as that of tha 

 ovary, but not always ; because certain changes may take place after 

 flowering. The commonest change is the obliteration in the growing 

 fruit of some parts which existed in the pistil at the time of flowering. 

 The ovary of a Horsechestnut, for instance, has three cells and two 

 ovules in each cell ; but the fruit never has more than three seeds, 

 and rarely more than one or two, and only as many cells. Yet the 

 vestiges of the seeds that have not matured, and of the wanting cells 

 of the pod, may always be detected in the ripe fruit. This oblitera- 

 tion is more complete in the Oak and Chestnut. The ovary of the 

 first likewise has three cells, that of the second six or seven cells, 

 each with two ovules hanging from the summit. We might there- 

 fore expect the acorn and the chestnut to have as many cells, and 

 two seeds in each cell. Whereas, in fact, all the cells and all the 

 ovules but one are uniformly obliterated in the forming fruit, which 

 thus becomes one-celled and one-seeded, and rarely can any vestige 

 be found of the missing parts. 



337. On the other hand, a one-celled ovary sometimes becomes 

 several-celled in the fruit by the formation of false partitions, com- 

 monly by cross-partitions, as in the jointed pod of the Sea-Rocket 

 and the Tick-Trefoil (Fig. 304). 



338. Their Kinds. In defining the principal kinds of simple fruits 

 which have particular names, we may classify them, in the first place 9 

 into, 1. Fleshy Fruits; 2. Stone Fruits-, and 3. Dry Fruits. 

 The first and second are of course indehiscent ; that is, they do not 

 split open when ripe to discharge the seeds. 



339. In fleshy fruits the whole pericarp, or wall of the ovary, 

 thickens and becomes soft (fleshy, juicy, or pulpy) as it ripens. Of 

 this the leading kind is 



340. The Berry, such as the gooseberry and currant, the blueberry 

 and cranberry, the tomato, and the grape. Here the whole flesh is 

 equally soft throughout. The orange is merely a berry with '4 

 leathery rind. 



