mjTACEM. 



409 



contain under their coats one or several fleshy embryoes, with 

 cotyledons often unequal and irregular, and short superior radicle 

 (figs. 457-459). More than thirty species of this genus have been 

 described ; these are probably forms or varieties of four or five species, 1 

 natives of the tropical regions of Asia. They are aromatic 2 trees or 



Citrus Aurantiiun. 



Figs. 457, 45S, 459. 

 Embryos (f ). 



shrubs, with branches often thorny, leaves persistent, alternate only 

 having one articulate foliole and a more or less dilated and winged 

 petiole. 3 The fragrant flowers are axillary and solitary, accom- 

 panied by sterile bracts, or disposed in few-flowered cymes with 

 centrifugal evolution. 



unequal faces. Their contents become modified ; 

 in the interior is secreted the acid and sweet 

 juice of oranges, lemons, &c. (Upon the forma- 

 tion of this complementary layer of the fruit 

 see Taegioni, in Giorn. Tosc. d, Sc, i. 575. — 

 Zucc, in Abh. d. Bay. Akad., iv. p. i. 159 ; 

 p. ii. 33, t. 66. — H. Bn., Aurardiac., 42. — 

 Cab., Sull. Pulp, che Invogl. i Semi (Firenz., 

 1864), 7, t. 1. 



1 Monabd., De Citr. Awrant. et Lim. 

 (Antwerp., 1561). — Feebab., Hesperid. (Roma, 

 1646).— Galles., Tr. du Citrus (Par., 1811). 

 D. Giard. di Firenze (1839) ; Gli Agrum. — 

 Risso & Poit., Hist. Nat. des Orang. (Par., 

 1818-19). — R(EJi., Syn. Hesperid. (For the 

 principal treatises on the genus, see Peitzel, 

 Thes., 444, 451.) — Wight & Aen., Prodr., i. 

 97. — Sieb. & Zrxcc, Fl. Jap., t. 15. — Geiseb., 

 Fl. Brit. W.-Ind., 132. — Benth., FL Austral., 

 i. 371.— Miq.„ Fl. Ind.-Bat., i. p. ii. 530.— 

 Wale., Rep., i. 382 ; ii. 504 ; v. 140 ; Ann., 

 vii. 535. 



- This is due to the numerous more or less 

 prominent vesicles full of an essential oil scat- 

 tered through most of the organs, leaves, flowers, 

 pericarp, &c. We observed in 1855 that these 

 reservoirs are formed first of a certain number 

 of secretive cells constituting a yellowish mass 

 embedded in the ambient tissues, and that later 

 a large channel is produced at this level which 

 crosses and forms a large lacuna, carpeted with 

 the remains of fine compressed cells. Maetinet, 

 who has studied the development of these 

 glands (in Ann. Sc. Nat., ser. 5, xiv. 199), does 

 not admit this opinion ; but it is easy to see that 

 what he substitutes for it only differs in the 

 mode of statement and the interpretation of 

 facts. 



3 Equal in size to the limb itself in certain 

 species of Citrus, especially C. Hyslrix DC. 

 (Cat. Sort. Monsp., 97; Prodr., n. 7). In 

 Pseudcegle the leaves are trifoliolate. 



