For further information on the subject of natural arrangements the 

 student should consult Dr. Lindley's ' Vegetable Kingdom.' 



EXORHIZyE. [EXOGEXS.] 



EXO'STEMMA (from ?, without, and aTt^^a, a crown) a genus 

 of Plants belonging to the natural order Cinchonacece. It has an 

 obovate 5-toothed calyx ; a corolla with a terete tube, and a 5-parted 

 limb with linear segments ; the anthers linear, exserted ; the capsule 

 crowned by the calyx, dehiscing from the apex through the dissepi- i 

 menta into two half-fruits ; the seeds girded by a membranous entire 

 border. The species are trees or shrubs, with lanceolate oval short- 

 stalkeil leaves, and stipules solitary on each side of the petioles. 



E. Caribaum, Quinquina Piton, Sea-side Beech, has ovate-lanceolate 

 acuminated glabrous leaves; axillary 1 -flowered pedicles, rather 

 shorter than the petioles ; the calyx bluntly 5-toothed ; the style and 

 stamens about equal in length to the corolla. It is a tree about 

 twenty feet high, and a native of the Caribbee Islands, Guadaloupe, 

 St. Domingo, Jamaica, Santa Cruz, and Mexico. This plant is the 

 Cinchona Caribtea of Jacquin and the C. Jamaicerurii of Wright. The | 

 capsules before they are ripened are very bitter, and produce a burning 

 itching when applied to the nostrils and lips. The bark is also bitter, 

 and possesses a tonic, febrifuge, and emetic action on the system, but 

 it does not appear to have either quinine or cinchonine in its compo- 

 sition. The bark is generally smooth and gray on the outside. Its 

 flavour, according to Dr. Wright, is at first sweet, with a mixture of 

 th* taste of horse-radish and aromatic oils, but afterwards it becomes 

 excessively bitter and disagreeable. When examined by the micro- 

 scope it presents innumerable shining crystalline points, which, 

 according to Guibourt, are some principle peculiar to the bark. 



E. Jtoribunda, Quinquina of St. Lucia, has elliptic acuminated 

 glabrous leaves; peduncles terminal, corymbose; flowers smooth; the 

 teeth of the calyx short, acute ; the capsules turbinate. It is a native 

 of the West India islands, among woods by the side of torrents. It is 

 the Cinchona floribunda of Swartz ; C. Sanctas Lucice of David, C. 

 montana of Badier, and C. Luciana of Yittmann. The bark is similar 

 to the last, and used as a substitute for the Peruvian bark, but 

 Pelletier and Caventou discovered no quinine or cinchonine in any 

 part of the plant. 



E. Souianum, Quinquina de Piauhi, has leaves obovate or ovate, 

 cute, smooth ; the corymbs few, flowered, terminal ; the capsules 

 scarcely an inch long, obovate, compressed, the valves usually 4-nerved; 



the seeds transversely oblong, with a broad wing all round. This 

 plant is a native of Brazil, and is used as a substitute for the Peruvian 



bark. Buchner found in it an alkaloid, which he called Esenbeckine, 

 on the supposition that this plant was au EsmbecTcia. The alkaloid 

 was probably cinchonine. 



E. Pcrurianum is the Cinchona Peruviana of Poiret. It has ovate- 

 oblong acute leaves, rounded at the base, the upper sessile and 

 cordate. It is a tree ten or twelve feet high, and grows in the colder 

 parts of Peru, on the declivities of the Andes, between the river 

 Chota and the village of Querocotillo, 3000 feet above the level of 

 the aea. The bark is very bitter, and has a sweetish taste, with a 

 nauseous smell. There are several other species of Exostemma, wbich 

 have also been used as cinchona barks, but the above are those which 

 are best known. 



(Don, Dichlamydeous Plants; Lindley, Flora Medico,; Bischoff, 

 Medicinich-Pharmaceutitche Botanik.) 



EYE. The organs appropriated to the sense of sight are distri- 

 buted very extensively, yet with that frugality which always regulates 

 the operations of nature in the construction of animals. All the 

 active species which live in the light are furnished with them ; the 

 rest are disqualified to possess as well as to profit by them, by their 

 limited powers of locomotion, or by constant residence in the dark. 

 In conformity with this rule, to which there are few if any exceptions, 

 these organs are occasionally associated with the lowest types of 

 animal development, and are sometimes absent in the highest. Thus 

 some radiated animals, most of the articulated tribes, and many of 

 the mollusca, have manifest organs of vision, and some of them are of 

 the most curious and artificial construction ; on the other hand, the 

 mole and the shrew-mouse, both vertebrated animals, and belonging 

 to the highest order of that class, the mammalia, are blind. They 

 have eyes, it is true ; but those of the mole are not larger than the 

 head of a pin, and are unprovided with optic nerves ; and the 

 equally imperfect eye of the shrew is covered with skin, from which 

 hair grows as on the rest of the body. Hence, even in the absence of 

 further evidence, we might conclude that if these animals have any 

 perception of light, it can only be sufficient to warn them back to 

 their haunts when by any accident they emerge to the day. But it is 

 more probable that they do not see at all; and that these rudimentary 

 organs, like the male nipple, exist only in conformity with the general 

 model of vertebrated construction." 



