ELATERIUM. 



ELECTRICITY OF ORGANIC BEINGS. 



498 



extremity of the pnesternum projecting beneath the head ; the apex 

 of the third and seven following joints of the antennae prolonged ; 

 mandibles unidentate ; maxillce with a single lobe ; palpi very short. 



C. denticornii (Latreille), the only species known, is from Cayenne. 



Nrmatodei (Latreille). Body nearly linear ; antenna: with the basal 

 joint elongated ; each of the five following joints in the form of a 

 reversed cone ; the remaining joints almost perfoliate, with the excep- 

 tion of the last, which is ovaL 



Species of this genus have been found in Europe and North 

 America. 



Ilemeripuf (Latreille). In this genus the parts of the mouth are 

 exposed, that is, not, as in the last two genera, hidden by the project- 

 ing process of the praesternum ; the antennae are flabellate at the apex 

 in the males. 



All the species of this genus are extra-European. 



In the genus Ctenifera ( Latreille), the antennae are pectinated in the 

 males, and deeply serrated in the females. 



The C. pcctinicarnis, an insect common in some parts of this country, 

 affords an example of this genus. The species is rather more than 

 half an inch in length, and of a brilliant metallic green or copper-like 

 colour : the female is larger and broader than the male. 



In the genus Elaier, aa now restricted, the antennae are simply 

 serrated. 



The E. cgnetu of Linnaeus will serve to illustrate this genus. This 

 species, which is common in some parts of England, is generally found 

 under stones on hilla of but little elevation, and which are more or 

 less covered with heath. It is about three-quarters of an inch in 

 length, and most commonly of a brilliant green colour; some speci- 

 mens however are blue, and others are of a brassy or bronze hue. 



The . noctiluctu, according to Latreille, also belongs to this genus. 

 This species is well known in South America, where it is called the 

 Fire-Fly.* It is rather more than an inch in length, of a brown 

 colour, and covered with an ashy down : on each side of the thorax 

 there is a round glossy yellow spot. These spots emit by night a 

 light so brilliant as to enable a person to read by it, and it is a com- 

 mon practice to place several of the insects together in a glass jar or 

 bottle for this purpose. This insect (with upwards of twenty other 

 species, all of which emit light by night) is now included in Illiger's 

 genus Pyrojihonu, The species of this genus are, some of them, from 

 each of the following localities : Brazil, Peru, Buenos Ayres, Chili, 

 Cuba, St. Domingo, and Guyana, 



In the genus Camjiylus (Fischer) the eyes are more prominent than 

 in the other Elattrida, and the head is protruded from the thorax ; 

 the antennae are inserted beneath a frontal projection on each side, and 

 the body is long and almost linear. 



One species of this genus is found in England, the C. diipar, which ia 

 of a yellowish colour. In some specimens the head, legs, and antennae 

 are black, and sometimes the elytra are black with abroad pale margin. 



ELATERIUM. [MOMOBDICA.] 



ELATINA'CEvE, Water- Pej,ptn, a natural order of Plants be- 

 longing to Lindley's Calycose group of Polypetalous Exogens. The 

 sepals are 3-5, distinct, or slightly connate at the base ; the petals 

 hypogynous, alternate with the sepals; the stamens hypogynous, 

 usually twice as numerous as the petals ; the ovary with from 3 to 5 

 cells, an equal number of styles, and capitate stigmas ; the fruit 

 capsular, 3-5 celled, with the valves alternate with the septa, which 

 usually adhere to a central axis ; the seeds numerous, with a straight 

 embryo, whose radicle is turned to the hilum, and little albumen. 

 The species belonging to this order are annual plants with fistulous 

 rooting stems, and opposite stipulate leaves, inhabitants of marshy 



This order is nearly allied to Caryophyllacett, from which it has 

 been separated by Cambessedes, on account of the different organi- 

 sation of the seeds, capsules, and stigmas. It agrees with Ifypericacerc 

 in many points, and especially in possessing receptacles for resinous 

 secretions, but differs in having a persistent central axis in the fmit, 

 definite stamens, and so forth. The species are found in marshy 

 places and under water in all parts of the globe. Cambessedes 

 arranged three genera in this order : 



1. Merimtea (named in honour of Prospero Merimes, an old 

 botanist), with a 5-parted calyx ; 5 petals ; 1 stamens ; 5 styles ; a 

 5-valved, 5-celled, many-seeded capsule, the valve separating, and 

 bent in at the margins so as to constitute dissepiments. This is a 

 South American genus, of which but one species, M, arcnarioidet, a 

 native of Brazil, has been described. 



2. Bergia (after Peter Jonas Bergius, professor of natural history 

 at Stockholm, and author of several works on botany), with a 5-parted 

 calyx ; 5 petals ; 5 styles approximate ; the capsule 5-valved, 5-celled 

 from the edges of the cell being bent inwards. There are four 

 species ; one is a native of Egypt, one of Java, one of the East Indies, 

 and one of the Cape of Good Hope. 



3. Elatine, with a calyx 3-4-parted ; 3-4 petals; 3-4 or 6-8 

 tameni ; 3 4 styles ; the capsules 3-4-celled, many-seeded, the seeds 

 cylindrical, terete, straight or bent. There are five species of this 

 genus. 



* Other inMfcts having the (tame power of emitting a light by night are 

 undoubtedly confounded with the present >pecies under the name of the 

 Hire. Fir. 



HAT. IliST. WV. V'.I. n. 



E. Hydropiper, Water-Pepper, has opposite leaves shorter then their 

 petioles, the flowers stalked or nearly sessile, with 8 stamens and 4 

 ovate petals ; the capsule roundish, depressed, 4-celled, the seeds bent 

 almost double, pendulous, four in each cell. It has rose-coloured 

 flowers. It grows under water, and is very common in ground 

 subject to inundations throughout France. It is a very rare plant in 

 Great Britain, and has been found only in Wales and Ireland. E. 

 hejrandra is a minute plant having 6 stamens. It forms small matted 

 tufts under water, and ia common in France, but rare in Great Britain. 

 E. tripetala of Smith is identical with this species. E. triandra has 

 been found in the neighbourhood of Ratisbon. E. alainastrum is 

 found near Paris. 



In addition to the above genera, Trtradiclit, Anatropa, and Tridia 

 are now enumerated. There are 6 genera and 22 species. 



(Don, DiMamydeous Plants ; Babington, Man. Brit. Bot.) 



ELATINE. [ELATINACE.E.] 



ELCAJA, an Arabian Plant, whose fruit is said to possess emetic 

 properties. Botanists call it Trichilia emelica. Forskahl describes it 

 as a large tree, with villous shoots, pinnated leaves, with entire oval- 

 oblong pedicellate leaflets, clustered flowers with 5 greenish-yellow 

 petals, 10 monadelphous stamens, and a downy capsular fruit about 

 an inch long, with 3 valves, 3 angles, and 3 cells, having 2 plano- 

 convex seeds in each cell. The tree is said to be called Roka, and 

 to be common on the mountains of Yemen. The fruit is sold at Beit 

 el fakih, for mixing with fragrant materials with which the Arab 

 women wash their hair. The fruit called ' Djour elkai* is reputed 

 an emetic. The ripe seeds mixed with Sesamum oil ara formed into 

 an ointment as a cure for the itch. 



ELDER-TREE. [SAMBUCUS.] 



ELECAMPANE. [INULA.] 



ELECTRA. [CELLARI.EA.J 



ELECTRIC-EEL. [ELECTRICITY OP ORGANIC BEINGS.] 



ELECTRICITY OF ORGANIC BEINGS. Plants and animals 

 under certain circumstances are known to exhibit electrical pheno- 

 mena. These however are not so constant or frequent as is sometimes 

 imagined. Considering the connection that is now known to exist 

 between the great forces of nature, as Light, Heat, Chemical Action, 

 and Electricity, it is perhaps matter of surprise that so few electrical 

 phenomena are exhibited by organised bodies. 



In Plants it appears that during growth electricity is developed. 

 Pouillet filled several pot with earth, and placed in them different 

 kinds of seeds, and then insulated them. During the process of ger- 

 mination no electric disturbance was discovered, but when the seeds 

 began to sprout a gold-leaf electrometer had its leaves separated at 

 least half an inch from each other. Pouillet concludes that the vege- 

 tation on the surface of the earth must produce a vast amount of 

 electricity, and be an active cause of its phenomena in the atmosphere. 

 Other observers have found that, by placing wires in the bark and 

 pith of a growing tree, they have obtained decided indications of the 

 presence of a galvanic current. These exhibitions of electric disturb- 

 ance are undoubtedly dependent on the chemical changes going on in 

 the plant, and this is one of the many instances in which we find one 

 force in nature representing another. Under the influence of heat and 

 light the chemical and attractive forces are brought into play, and the 

 motile force of the growth of the plant as well as electrical phenomena 

 are the result. 



In the Animal Kingdom the same indications of the presence of 

 electricity is afforded during the activity of the vital functions. 

 Matteucci has observed a considerable deflection of the galvanometer 

 when wires were connected with it passing from the liver and stomach 

 of a rabbit. Other experimenters have obtained similar results. It 

 has been supposed that these phenomena were due to the chemical 

 changes going on in the body of the animal, but they cease on the 

 death of the animal. Free electricity is excited by the movements 

 of the human body. This is made evident by rubbing the feet on a 

 woollen rug, when, on applying the hand to a gold-leaf electrometer, 

 the presence of electric disturbance is indicated. Some persons are 

 more liable to this development than others ; and Dr. Carpenter says 

 there are persons " who scarcely ever pull off articles of dress which 

 have been worn next the skin without sparks and a crackling noise 

 being produced, especially in dry weather." 



Recent experiments of Matteucci and Du Bois-Raymond have shown 

 not only that free electricity is developed in animal bodies, but that 

 there is a tme galvanic current both in the muscles and nerves. 

 Galvani attributed the movements, first observed by his wife, induced 

 hi a frog's leg by plates of copper and zinc, to a purely animal action. 

 Volta shewed that the movements observed by Galvani were dependent 

 on the chemical action developed in the metals. Matteucci observed 

 the peculiar sensibility of the nerves and muscles of the frog to gal- 

 vanic action, and made use of the leg, prepared as a galvanometer, in 

 many of his experiments. The mode of using it was simply to take 

 the leg of a recently-killed frog with the crural nerve dissected out of 

 the body, but remaining in connection with it. The leg was then 

 inclosed in a glass tube covered with an insulating vr.ruish, and the 

 nerve allowed to hang freely at its open end. When two points of 

 the nerve thus prepared are brought in contact with any two sub- 

 stances in a different electrical state, the muscles of the frog's leg are 

 thrown into contraction. By this ' galvanscopio frog ' Matteucci was 



2 K 



