408 



NATURAL HISTORY OF PLANTS. 



consists of species of Feronia, with numerous polyadelphous stamens 

 united round the hypogynous disk in very unequal bundles (of 

 which some may even be reduced to one stamen), and with 

 ovary cells multiovulate and indefinite in number ; or we might 

 describe it as consisting of a species of JEgle, whose stamens, inserted 

 round a circular disk instead of being free, are united into a variable 

 number of unequal bundles. 1 The cupuliform calyx has five teeth 



Citrus Aurantiwm. 



Fig. 455. 

 Long. sect, of flower (;!). 



Fig. 456. 

 Transverse section of fruit. 



(or a variable number, from four to six), and generally five imbricated 

 petals ; but the number of the latter may also vary from four to 

 eight, or more. The fruit is a berry, of which oranges and lemons 

 furnish a familiar example, and easily show the organization. The 

 wall is not thick, although composed of three different layers ; but 

 the numerous cells contain, besides a variable number of seeds, a 

 soft pulp, more or less acid or sweet, formed by hairs and elongated 

 cells, secreting a juice abounding in their cavity, and which, spring- 

 ing from the surface of the endocarp, advance into the cells, which 

 they obstruct, and whose seeds they definitely envelope. 2 These 



1 In Papeda and Pseud (Pf/le the bundles of 

 stamens are more or less indicated ; but the 

 filaments are free, or nearly so ; tbey may be 

 made sections of the genus Citrus, The pollen 

 of the Aurantiacea.', studied by H. Mom (in 

 Ann. Sc. Nat., ser. 2, iii. 330) is " ovoid ; three 

 folds; in water spherical with three papillose 

 bands." 



2 These cells are formed by the hairs of the in- 

 ternal surface of the pericarp. At the opening of 

 the flower the interior epidermis of the ovary 

 already presents small prominent teats ; these are 



accrescent cells enlarging towards the middle 

 of the wall. Others increase in the same way 

 to the right and left of the first as far as the 

 partition. They do not rise thus upon the 

 entire partition as far as the placentas; the 

 phenomenon usually stops very far from the 

 internal angle. Later, these cells whose summit 

 is advanced towards the placentary angle be- 

 comes acute at die apex, large towards the 

 middle of their length, and then more or less 

 pediculate; after which they are compressed 

 one by the other, and their surface then presents 



