A c i 



with a tuft of <vithered male florets, like a taflel. The 

 intermediate jlorets feem to be abortive, though furnifhed 

 with the mod confpicuous p'lfl'tU. 



2. A. fpathulata. Spatulate Acicarpha. Brown Tr. of 



Linn. Soc. *. 12. 129. — Leaves fpatulate, moftly entire 



Sent from Brazil by Mr. Sellow. A fmooth, difFufe, 

 apparently annual plant, with angular afcending branches. 

 Leaves fcattered, ftalked, without Jlipulas, fpatulate, with a 

 very (hort little point, rather thick, and perhaps glaucous, 

 an inch and a half long ; the lower ones fometimes toothed 

 from above the middle. Footjlalis linear, a little dilated at 

 the bafe ; the lowermoft longeft. Heads oi jiowers yellow, 

 folitary ; either ftalked and oppofite to the leaves, or ter- 

 minal and nearly feffile. Involucrum of five leaves in a 

 fimple row, longer than the flowers. Receptacle conical, 

 (lender, chaffy, with lanceolate pointed fcales. Florets 

 tubular, uniform, fmooth. Thofe of the circumference in 

 two or three rows, with perfeft Jlamens as well as piftils. 

 Tube of the corolla (lender, cylindrical, clofely united to 

 the germen and bafe of the Jlyle ; limb funnel-ihapcd, five- 

 cleft, fegments parallel at the edges, half-lanceolate, flat, 

 three-ribbed. Stamens five, inferted into the corolla, alter- 

 nate with its fegments, their Jllaments, as well as the lower 

 half of the anthers, united into a tube. Germens combined, 

 each crowned with a five-cleft partial calyx, whofe teeth, 

 alternate with the fegments of the corolla, become fpinous, 

 each germen containing one pendulous yfc(/. Style thread- 

 Ihaped, fmooth. Stigma fimple, obtufe, rather hairy. The 

 numerous upper Jlorets are rather fmaller, with a m.em- 

 branous calyx, and imperfett germens. The ripe fruit, ori- 

 ginating from the florets of the circumference, confifts of 

 clofe pericarps, combined together, not burfting, each 

 crowned with its own enlarged fpinous calyx. Seed ovate, 

 pendulous. Albumen flefhy, large, white. Embryo nearly 

 eylindrical, central, about the length of the albumen, with 

 two linear cotyledons. By this account it appears that Mr. 

 Brown differs from M. de Juffieu, in thinking the prefent 

 genus belongs to the Linnaean order of Aggregate, and not 

 to the Compoftd. This laft account of the fruit is evidently 

 more natural than the above, and the charafter, if Mr. 

 Brown, which we doubt not, be correci, muft be altered 

 to " Seeds crowned with the fpinous partial calyx." 



ACID, Acidification, in Chemiflry. When thefe 

 articles were written for the Cyclopjedia, the theory of 

 Lavoifier, that oxygen was the only principle of acidification, 

 was almoft univerfally received. Since that period, how- 

 ever, a great revolution has taken place in chemiftry, and 

 the doftrine in queftion is now no longer admitted. This 

 indeed has been noticed in fubfequent parts of this work, 

 more efpecially under Oxygen and Oxymuriatic Acid ; 

 fo that little more is necefiary than to refer our readers to 

 thefe articles. It may not be deemed fuperfluous, however, 

 to mention here very briefly the difcoveries that have led to 

 thefe important changes. 



The firft circumftance which gave the death-blow to the 

 doftrine of Lavoifier, v^as the demonftration by Gay 

 LufTac and Thenard, and more efpecially by Davy, that 

 oxymuriatic acid, or chlorine, as it is now termed, contains 

 no oxygen, but is a fimple elementary fubftance. Chemifts 

 indeed had never been able to demonilrate fatisfaftorily that 

 oxygen aftuaUy exifted in this fubftance ; but mifled by the 

 plaufibility of the Lavoiilerian doftrines, had tacitly ad- 

 mitted its prefence from analogy : and fo ftrongly was this 

 belief founded, that there are a fev.', we believe, who 

 adhere to the old opinions even to the prefent time. 



More recently, however, the old opinions have been ren- 

 dered ftill further improbable .and the new ones corroborated 



AGO 



by the difcovery of iodine and cyanogen; the one an ele- 

 mentary, the other a compound fubftance, both which 

 have been unequivocally demonftrated to form acids by 

 combining with hydrogen. The analogy, alfo, of fulphu- 

 retted and telluretted hydrogen, compounds free from oxy- 

 gen, but poflefling the properties of acids, have been like- 

 wife urged in proof of the new opinions, and as quite irre- 

 concileable with thofe of Lavoifier. 



Our readers will find further information on this fubjeft 

 in the articles Chj.orike, Cyanogen, Iodine, Muria- 

 tic Acid, Oxygen, and Oxymuriatic Acid. 



ACINACIFORME, Folrtm, in Botany, a Scimitar- 

 fhaped Leaf, is fcarcely ufed but for one fpecies of Mefem 

 bryanthemum, which bears this fpecific name. (See Leaf. 

 It is of a fucculent texture, comprefted, one edge conve 

 and thin, the other ftraighter and thick. 



Acinaciforme, Pericarpium, a Seed-veffel of a fimilar 

 ftiape, is exemplified in the cells of the capfule of the fame 

 genus of Mefembryanthemum ; fee Linn. Phil. Bot. 224. 



ACINUS, in Botany and Vegetable Phyfiology, a Grain, 

 IS technically ufed for each pulpy portion, containing a foli- 

 tary feed, of a compound Berry. (See Bacca.) The 

 fruit of tlie Rafpberry, Bramble, &c., confifts of feveral 

 acini; and perhaps the fame term may be applied to the 

 fcparate portions of a Mulberry, though originating in the 

 calyx of each flower become pulpy. In Pajiflora the cap- 

 fule is lined with very juicy acini, each lodging a fingle feed. 

 Gjertner improperly extends the above term to the fimple 

 many-feeded berries of the Vine, Goofeberry, &c. The 

 laft-mentioned fruit, in an early ftate, rather refembles the 

 Pajifora. 



ACONITUM, in Botany, (fee our former article,) has 

 received confiderable elucidation from profefTor De CandoUe, 

 in his Regni J'^egetabilis Syjlema Naturale, v. 1. 364, where 

 this genus is treated of as one of the natural order of Ra- 

 NUXCULACE.E. ( See that article. ) Its generic references 

 are, Linn. Gen. 274. Schreb. 368. Willd. Sp. PI. v. 2. 

 1232. Mart. Mill. Dift. v. I. Ait. Hort. Kew. v. 3. 321. 

 Sm. Prodr. Fl. Gric. Sibth. v. I. 372. Purfti 372. Jufl". 

 234. Tourn. t. 239, 240. Lamarck lUuftr. t. 482. Gsertn. 

 t. 65. " Koelle Monogr. 1 788. Erlang. in 8vo." — Clafs 

 and order, Polyandria Pentagynia. Nat. Ord. MultifiUqua, 

 Linn. Ranunculaceit, Juft^. De Cand. 



Eff. Ch. Calyx none. Petals five ; the uppermoft 

 vaulted. Neftaries two, ftalked, recurved. Capfules three 

 or five. 



M. De Candolle, following Juffieu's view of the fubjeft, 

 gives the following charafters, ufing the term fepala for 

 calyx-leaves, and pet ala for neSaries. 



Calyx of five petal-hke, deciduous leaves ; the upper one 

 (hood) large, concave, helmet-ftiaped ; two lateral ones, 

 (wings,) orbicular; two lowermoft oblong. Petals five, 

 fometimes irregular in number ; three very minute, claw- 

 fhaped, often converted into ftamens ; two uppermoft with 

 long claws, hooded, ftieltered under the helmet-thaped leaf 

 of the calyx, dilated at the top into a bag, whofe bottom, 

 the fummit, or fpur, of the petal, is callous, incurved, its 

 mouth extended into an oblong, emarginate limb, or lip. 

 Stamens indefinite. Capfules three to five, with an indefi- 

 nite number of feeds. 



Perennial herbs, with tuberous roots, whofe knobs in 

 fome inftances bear fibres, in others are oblong, and mixed 

 therewith. Stem leafy. Leaves ftalked, deeply palmate, 

 with from three to five fegments, variouily cut, cloven and 

 toothed. Clnfers terminal. Slalis fingle-flowered, from the 

 bofoms of the bra^cas, each bearing two fmaller braffeas. 



Flowers 



