811 



FILAMENT. 



FI LICES. 



unrounded and overtopped by one or tiro bluut leaves. It smells 

 liko tansey. The (tern is mostly erect, with abort branches below. 

 The heads an rather Urge, 10 to 20 in a cluster. 



(Babington, MantuJ of Bnluh Botany.) 



FILAMENT, in Botany, the part of the stamens which bears the 

 anther. It U sometimes long and slender, heuoe iU name filament. 

 In some plants however it is nearly or altogether absent, and not 

 unfrequently flat and broad. [STAMEN.] 



F1I.AKIA. fEsTOlOA.] 



FILHEKT. [CoBTLUS.] 



KILE FISH. [BAUBTBS.] 



FI'LICES, or FILtCA'CE.f:, a natural order of Plants, being the 

 highest group of the class Cryptogamia, or Acrogeus. The species are 

 floweriess planU, consisting of leafy fronds, which ore produced from 

 a rhisoma unfolding in a spiral manner, and traversed by veins which 

 form definite parts on the under surface, and produce unilocular, rarely 

 multilocular, cason containing reproductive sporules. 



The parts of these plants which require most attention in their 

 study, and on modifications of which modern classifications depend, 

 are the veins and organs of reproduction. The veins are either 

 produced equally from both sides of a midrib, or they radiate from 

 the base or axis of development, or from one aide of an eccentric or 

 unilateral cost*. They are either simple, or once or repeatedly 

 dichotomously branched, or the primary veins are pinnate ; the 

 branches either simple or forked. Their apices are either free or 

 they are combined by various forms of anastomosis. The organs of 

 reproduction consist of a sporangiferoua receptacle, which is a thick- 

 ened point or lengthened portion of the ultimate veuules or veinleU. 

 It is generally superficial, sometimes immersed in the substance of 

 the frond, or considerably elevated, and then globose or columnar. 

 The sporangia, theca.-, or spore-cases, are transparent, globose, oval, 

 or pyriform unilocular cases, each girded by a more or less complete 

 elastic articulated ring, or destitute of a ring ; then sometimes oblong, 

 opaque, and multilocular, and usually pedicillate. The son are col- 

 lections of sporangia, and have the same form, position, and direction 

 as the receptacles. They are either nuked, or each sorus is furnished 

 with a membranaceous covering of various forms which rises from 

 the receptacle. This covering is called an indusium, and is a plane, 

 or vaulted, or cup-shaped membrane, produced from the receptacle 

 of each sorus, and is generally deciduous as it becomes replicate. 

 Often the entire margin (or lobules of the frond) is changed in texture, 

 and forms an accessory indusium. Sometimes the whole of the son 

 of each segment are included within a universal indusium which is 

 formed by the revolute margin of fertile contracted fronds. 



The following account of the reproduction of the Kerns is given in 

 a Report to the British Association in 1851, on the higher Cryptoga- 

 mous Plants, by Mr. Uenfrey. Speaking of the Ferns, Mr. Henfrey 

 says: 



" This class formed for a long time the great stumbling-block to 

 those who sought to demonstrate the existence of sexuality in plants. 

 The young capsules were generally considered to be the analogues of 

 the pistillidia of the Mosses, and the young abortive capsules which 

 frequently occur among the fertile ones were supposed by some authors 

 to represent the antheridia, Mr. Griffith noticed a structure which 

 he was inclined to regard as the analogue of the antheridium in certain 

 of the ramenta upon the petioles. 



" In the year 1844 Professor Niigeli published an account of his 

 observations on the germination of certain ferns, and announced the 

 discovery of moving spiral filaments closely resembling those of the 

 C'hura, on certain cellular structures developed upon the pro-embryo 

 or cellular body first produced by the spore. It is not worth while 

 to enter into an analysis of his observations, as they have since been 

 clearly shown to have been very imperfect ; it is sufficient to state 

 that be only described one kind of organ, and from his description it 

 is evident that he confounded the two kinds since discovered, regard- 

 ing them as different stages of one structure. The announcement of 

 this discovery seemed to destroy all grounds for the assumption of 

 distinct sexes, not only in Ferns but in the other Cryptogams, since it 

 was argued that the existence of these cellular organs, producing 

 spiral filaments, the so-called spermatozoa, upon the germinating 

 fronds, proved that they were not to be regarded as in any way con- 

 nected with the reproductive processes. 



"But an essay published by the Count Suminski in 1848 totally 

 changed the face of the question, and ojtened a wide field for specula- 

 tion and investigation on this subject, just as it was beginning to fall 

 into disfavour. Count Suminski's paper gives a minute history of the 

 course of development of the Ferns, from the germination of the spore 

 to the production of the regular fronds ; and he found this develop- 

 ment to exhibit phenomena as curious as they were unexpected. The 

 cellular organs seen by Mageli were shown to bo of two perfectly dis- 

 tinct kinds, and moreover to present characters which gave great 

 plausibility to the hypothesis that they represented reproductive 

 organs ; moreover, this author exprevly stated that he had obtained 

 absolute proof of sexuality by observing an actual process of fertiliza- 

 tion to Uke place in the so-called ovules, through the agency of the 

 spiral filaments or spermatozoa. The main points of his paper may 

 be briefly summed up as follows : The fern-spore at first produces 

 a filamentary process, in the end of which cell-development goes on 



until it is converted into a Marchantia-b'ke frond of small size and 

 exceedingly delicate texture, possessing hair-like radicle threads on its 

 under side. On this under side become developed, in variable num- 

 bers, certain cellular organs of two distinct kinds. The first, whi.-h 

 be terms antheridia, are the more numerous, and consist of somewhat 

 globular cells seated on and ariaiug from single cells of the cellular 

 Marchantia-like frond. The globular cell produces in iU interior a 

 number of minute vesicles, in each of which is developed a spiral 

 filament, coiled up in the interior. At a certain epoch the globular 

 cell bursts, and discharges the vesicles, and the spiral filaments moving 

 within the vesicles, at length make their way out of them, and swim 

 about in the water, displaying a spiral or heliacal form, and consisting 

 of a delicate filament with a thickened clavate extremity ; this, the 

 so-called head, being said by Count Suminaki to be a hollow v. 

 and to be furnished with six or eight cilia, by means of which the 

 apparently voluntary movement of the filament is supposed to be 

 albaM. 



" The second kind of organ, the so-called ' ovules,' are fewer in 

 number and present different characters in different stages. At first 

 they appear as little round cavities in the cellular tissue of the pro- 

 embryo, lying near its centre, and opening on the under side. In the 

 bottom of the cavity is seen a little globular cell, the so-called 

 'embryo-sac.' It is stated by Count Summoki that while the ovule is 

 in this state one or more of the spiral filaments make their way into 

 the cavity, coming in contact with the central globular cell. The 

 four cells bounding the mouth of the orifice grow out from the 

 general surface into a blunt cone-like process, formed of four parallel 

 cells arranged in a squarish form, and leaving an intercellular canal 

 leading down to the cavity below. These four cells become <li 

 by cross septa, and grow out until the so-called ovule exhibits exter- 

 nally a cylindrical form composed of four tiers of cells, the uppermost 

 of which gradually converge and close up the orifice of the caual 

 leading down between them. Meanwhile the vesicular head of one of 

 the spiral filaments has penetrated into the globular cellule of the 

 embryo-sac, enlarged in size and undergone multiplication, and in 

 the course of time displays itself as the embryo, producing the first 

 frond and the terminal bud, whence the regular fern-stein is deve- 

 loped. In considering the import of these phenomena, the author 

 assumes the analogy here to be with the process of fertilisation in 

 flowering plants, as described by Schleiden, regarding the production 

 of the embryo from the vesicular head of the spermatozoa as 

 representing the production of the phanerogamous embryo, from the 

 end of the pollen tube after it has penetrated into the embryo-sac. 



" The promulgation of these statements naturally attracted great 

 attention, and since they appeared we have received several contribu- 

 tions to the history of these remarkable structures, some confirmatory, 

 to a certain degree, of Sumiuski's views ; others altogether opposed t 

 them. 



" In the early part of 1849 Dr. Wigand published a series of 

 researches on this subject, in which he subjected the assertions of 

 Suminski to a strict practical criticism ; the conclusions he arrived at 

 were altogether opposed to that author's views respecting the supposed 

 formation of the organs, and he never observed the entrance of the 

 spiral filaments into the cavity of the so-called ovule. About the 

 same time M. Thuret published a series of observations on the 

 ' Antheridia of Ferns.' In these he merely confirmed and corrected 

 the statements of Niigeli respecting the antheridia, and did not notice 

 the so-called ovules. 



" Towards the close of the same year Hofmeister confirmed part of 

 Sumiuski's statements, and opposed others. He stated thut he hod 

 observed distinctly the production of the young plant (or rather the 

 terminal bud for the new axis) in the interior of the so-called ovule ; 

 but believed the supposed origin of it from the end of the spiral 

 filament to be a delusion. He regards the globular cell at the base of 

 the canal of the ovule as itself the rudiment of the stem, or enihryo- 

 nal vesicle (the embryo originating from a free cell produced in this), 

 analogous to that produced in the pistillidia of the Mosses. He also 

 describes the development of the ovule differently, saying that the 

 canal and orifice are opened only at a late period by the separation of 

 the contiguous walls of the four rows of colls. 



" About the same time appeared an elaborate paper on the same 

 subject by Dr. Hermann Scnacht, whose results were almost identical. 

 Ho found the young terminal bud to be developed in the cavity <!' 

 one of the so-called ovules, which were developed exactly in th, 

 same way as the pistillidia of the Mosses. He stated also that tho 

 cavity of the ovule is not open at first, and he declares against the 

 probability of the entrance of a spiral filament into it, never having 

 observed this, much less a conversion of one into an embryo. In tho 

 essay of Dr. Metteuius, already referred to, an account of tin- develop- 

 ment of tho so-called ovules is given. His observations did not decide 

 whether the canal of tho ovule, which he regards as an intercellular 

 space, exists at first, or only subsequently, when it in entirely closed 

 above. Some important points occur in reference to the contents of 

 the canal The contents of the canal in a mature 

 of a continuous mass of homogeneous tough substance, in which line. 

 granules, and here and there large corpuscles, are embedded. Hi 

 down to the globular cell, or embryo-sac, and is in contact with it. 

 ThU mass cither fills the caual or diminishes in diauieter from the 



