82 THE FRUIT. [CHAP. 



Cowslip, but in these plants there is no trace of dis- 

 sepiments, the ovules originating independently of the 

 enclosing carpels. 



In Pea, Columbine, and other apocarpous pistils, the 

 carpels of which contain several ovules inserted upon the 

 ventral suture, the placentation may be described as 

 sutural. The sutural placentation of apocarpous pistils 

 is, of course, essentially the same as the axile placentation 

 of syncarpous pistils. 



22. OVULES originate as microscopic cellular projec- 

 tions, which either grow straight out into the cavity of 

 the ovary or, owing to unequal development at the base 

 or sides, become curved upon themselves like a horse- 

 shoe, or actually inverted, so bringing the organic apex 

 of the ovule into contact with the placentary surface. 

 Although ovules are generally borne upon the carpellary 

 margins, and consequently are of foliar origin, yet there 

 are numerous cases, more especially in plants with a one- 

 celled ovary and a solitary ovule from the base of its 

 cavity, in which the ovule may be regarded as developed 

 directly from the floral axis, either at its organic apex or 

 immediately by the side of it. The form and behaviour 

 of the ovule, however, are by no means affected by its 

 relation, in respect of origin, whether to the carpellary 

 leaves or axis. 



23. The structure of the FRUIT deserves careful atten- 

 tion, especially as there is scarcely any part of the plant 

 more liable to be misunderstood. We must learn from 

 what part, or parts, of the flower the fruit results, and 

 how to distinguish fruit from seed; for some common 

 fruits are constantly misnamed seeds, and sometimes 

 seeds are mistaken for fruits. 



Seeds are almost invariably contained in a seed-vessel 

 called the pericarp, and the pericarp may consist either 

 of the ripened ovary only, or if the ovary be inferior, of 

 the calyx-tube combined with the ovary. 



In the case of Buttercup, we have already learned 

 that the fruit consists of as many distinct carpels as there 

 were carpels in the pistil of the flower. Each carpel con- 

 tains one ovule in flower, and one seed in fruit. The 

 pistil of Buttercup we called apocarpous, and the same 

 term applies to the fruit. In like manner \ve may apply 



