236 The Natural System of Botany. 



On examining the leaves of an Orange or Lemon tree, they 

 will be found covered with minute yellowish or semi-transparent 

 dots. These are filled with an oil of peculiarly pungent taste 

 and very fragrant smell, which is especially perceived when 

 the leaves are crushed by the fingers. These little cavities 

 exist not only in the leaves and fruit, but in the leafy parts of 

 the flower, which owes to them most of its fragrance. It will 

 also be observed that the leaves are jointed, or articulated at 

 the junction of the blade with the petiole, and that the latter is 

 expanded into a sort of supplementary leaf, by the develope- 

 ment of a narrow blade from each side. In some species, the 

 leaves are pinnate ; and it sometimes happens that the leaflet 

 of one side only is developed, or that even both are absent, so 

 that the petiole, then much enlarged, has to perform the func- 

 tions of a true leaf. The calyx is cup-shaped, having three or 

 five sepals^ which fall off early. The number of petals is the 

 same as that of the sepals, and in the orange their color is 

 white, dotted with green. The stamens are equal in number 

 to the petals, or twice that number ; their filaments are flat- 

 tened, sometimes united at the base, and sometimes free. The 

 ovary is nearly globular, and composed of several adherent 

 carpels. The style is thick, and the stigma slightly divided. 

 Each cell of the ovary has a double row of ovules, a large 

 proportion of which perish during the ripening of the fruit, 

 and in the orange and its nearest allies, the cavity of the seed- 

 vessel becomes filled up with a pulp consisting of separate 

 vesicles, each containing a portion of the sweet-acid fluid. The 

 aggregation of these vesicles cannot be distinctly seen in the 

 usual state of the orange, but in an over-ripe specimen, they 

 are very easily separable. 



The various species of the Orange Tribe are nearly all na- 

 tives of the East Indies and China, whence they have been 

 introduced into other countries within or near the tropics. 

 They nearly all contain sugar, citric acid, an aromatic essen- 

 tial oil, and a bitter principle, having tonic properties, combined 

 in various proportions in different fruits. Thus, in the common 

 Orange the sugar prevails, and the acid, when the fruit is ripe, 

 is subordinate. In the Lemon, the acid is always predominant 

 in the pulp, and the oil is more abundant in ftie rind. In the 



