D I O N Y X D I O S C O R M. 



283 



ontal position. While so spread open, should a 

 lirsty or honey-seeking fly, or other insect, venture 

 etvveen the leaflets so as to touch the gland, they 

 istantly start up together with considerable force, and 

 hitch the prisoner ; nor can the intruder easily extri- 

 ate itself, because the inner edges of the leaflets are 

 :irnished with opposing ranks of short bristles, which 

 hut into each other like the teeth of a rat-trap ; so 

 liat a fly has no means of escape, more especially as 

 he leaflets do not open again for many hours. Tho 

 ame motion is produced by touching the gland with 

 he point of a straw or other body. 



Some naturalists are of opinion that this extraordi- 

 lary mechanism of the plant is a provision for supply- 

 ug itself with putrified animal food ; and have gone 

 ;o far as make the plant catch morsels of raw beef or 

 nutton, with a view to fattening, or increasing its 

 ,-olume. Nay, more, that the plants so feasted grew 

 he better for it ! but this requires confirmation. 



The vulgar name of the Dioncea is " Venus's fly- 

 Tap ;" it is a low inconspicuous marsh plant, and, when 

 cultivated in nurseries for sale, is planted in bog-earthy 

 :urf in a pot kept constantly in a pan of water, as the 

 plant must never be allowed to get dry; but by no 

 means should it be ever flooded. Whether kept in a 

 greenhouse or frame, they should have a hand-glass 

 placed over them, to ensure a more equable degree of 

 moist air : at the same time fresh air is necessary, th 

 hand-glass never being kept quite close. 



DIONYX (Dejean). A curious genus of minute 

 coleopterous insects, belonging to the family Psela- 

 phidte, allied to Statists, but having the labial palpi 

 armed laterally with several spines ; the antennae have 

 the four last joints very long. A single specimen ol 

 this curious insect has only yet been discovered : it 

 was captured by Dejean, on the wing, in the even- 

 ing, in the department of Aude, during his militar} 

 campaigns. 



D1OPSIS (Linnaeus). A genus of dipterous insects 

 belonging to the great family Muscidte, and distin- 

 guished from every other dipterous genus by having 

 the eyes and antenna) placed at the extremity of horny 

 slender footstalks, rising from the sides of the head 

 and being in some species as long as the entire body 

 which gives these insects a very remarkable appear 

 ance. They are of great rarity, and seldom found ii 

 collections. They inhabit the tropical climates o 

 India and Africa, and but little is known of their habit? 

 Above a score distinct species are described in a 

 monograph upon the genus, published in the last par 

 of the Transactions of the Linnean Society. 



DIOSCOREA (Linnaeus). A genus of herba 

 ceous plants, some few of which are eminently usefn 

 to the inhabitants of the countries where they natu 

 rally abound. LinnJEan class and order, Diced 

 Hexandria, and natural order Dioscorece ; Generi 

 character : perianths superior, six-cleft, persisting 

 stamens inserted into the base of the perianths 

 filaments awl-shaped ; anthers two-celled ; styles sim 

 pie ; capsule triangular, three-celled, in each two com 

 pressed winged seeds. The D. alala is the yam o 

 India. The tubers are as large as a child's heac 

 rough and black exteriorly, but when boiled, remark 

 ably white and mealy within, and very little inferio 

 to the best potato. They affect light sandy land ; an 

 in some of the East-India port towns, may be had i 

 considerable quantities for ship's stores, which kee 

 well for a month or two on board ship. In our ho 

 house collections they are grown in light soil, an 



ained up to stakes or upon a trellis, and are in- 

 reased by parting the roots. These, however, are 

 ever cultivated for use. 



DIOSCORECE, the yam family,a natural order ot 

 monocotyledonous plants, containing five or six known 

 enera and upwards of fifty species. It is nearly 

 Hied to Smilacea; in structure and habit, but differs 

 n the character of its ovary, its capsular fruit, and in 

 ts albumen, having a large cavity. In many respects 

 t approaches the dicotyledonous structure. 



Its essential characters are : flowers dioecious ; 

 >erianth six partite ; in the sterile or male flowers 

 here are six stamens inserted into the base of the 

 egments of the perianth ; in the fertile or female 

 lowers, the ovary is three-celled, each cell containing 

 >ne or two seeds ; style deeply trifid ; stigmas undi- 

 r ided ; fruit leaf-like, compressed, with two of its cells 

 ometimes abortive ; seeds flat, compressed ; embryo 

 mall, included in a large cavity of the cartilaginous 

 ilbumen, near the hilum. 



The plants of this order are twining shrubs, with 

 ilternate, occasionally opposite leaves, which are 

 generally reticulated with veins, as in the dicotyledo- 

 nous plants. The flowers are small, spiked, and have 

 rom one to three bracteas. 



They are found in tropical countries in both hemi- 

 spheres, and possess in general mucilaginous and nutri- 

 tive properties. 



The chief genera of the order are, Dioscorea, Raja- 

 nia, Testndinaria, Oncus, and AZchma. Tamus, or the 

 alack bryony, which was formerly included in this 

 order, is by Loudon and others referred to a distinct 

 order, called Tamcae. 



Dioscorea furnishes numerous species which are 

 found in the East and West Indies, and in North and 

 South America. They are commonly known by the 

 name of yams, and are interesting as furnishing large 

 fleshy, sweet tubers, which are considered an import- 

 ant article of food in all tropical countries. 



Dioscorea saliva, the common yam, is largely culti- 

 vated in the West Indies, where it serves for food to 

 the negroes. It yields large thick tubers a foot broad, 

 which have a mealy taste, and are esteemed nutritive 

 and easy of digestion. They are eaten instead of 

 bread, either roasted on the embers or boiled. The 

 flour got from them is made into puddings. The flesh 

 of the yam is white or purplish arid viscid, but becomes 

 farinaceous and mealy when dressed. The fresh 

 juice of the root is acrid, and excites itching on the 

 skin. There are many varieties of the root. Dios- 

 corea aciJeata is by some looked upon merely as an, 

 improved variety of the common yam. It is exten- 

 sively cultivated, and yields tubers which are fre- 

 quently three feet long, and weigh thirty pounds. 

 All the edible species and varieties of Dioscorea are 

 propagated in foreign countries like the common 

 potato, but they arrive much sooner at maturity. 

 They are planted in August, in rows two feet apart, 

 and eighteen inches distant in the rows, and they are 

 ripe in November or December. 



Tcstudinaria elephantipcs, common elephant's foot, 

 is a native of the Cape of Good Hope, and is fre- 

 quently cultivated in green-houses in this country. 

 This plant has a singular appearance on account of its 

 large fleshy root, a foot in diameter, which rises above 

 ground and is covered with angular brown knobs 

 having a tesselated aspect. The name testudinaria is 

 derived from the resemblance between this root and 

 the clumsy shell of some huge tortoise. The term 



