813 



FILICES. 



FILICES. 



814 



blind end of the canal down to the embryo-sac; in other cages it 

 possesses the form represented by Sumiuski, having a clavate enlarge- 

 ment at the blind end of the canal, and passing into a twisted filament 

 below ; in this latter shape it may frequently be pressed out of 

 isolated ovules under the microscope, and then a thin transparent 

 membrane-like layer was several times observed on its surface. In 

 other cases the contents consisted of nucleated vesicles, which emerged 

 separately or connected together. 



" The embryo-sac consists of a globular cell containing a nucleus, 

 and this author believes that the commencement of the development 

 of the embryo consists in the division of this into two, which go on 

 dividing to produce the cellular structure of the first frond. 



" With regard to the contents of the canal the author says, ' Although 

 I can give no information on many points, as in regard to the origin 

 of the contents of the canal of the ovule, yet my observations on the 

 development of the ovule do not allow me to consider them, with 

 Suminski, as spiral filaments in course of solution ; just as little 

 have I been able to convince myself of the existence of the process 

 of impregnation described by that author. It rather appears to me 

 that the possibility of the entrance of the spiral filaments and the 

 impregnation cannot exist until the tearing open of the blind end of 

 the canal in the perfectly-formed ovule, as after the opening of the 

 go-called ' canal of the style ' in the pistillidia of the Mosses." 



" Another contribution has been furnished by Dr. Mercklin, the 

 original of which I have not seen, but depend on analyses of it 

 published in the ' Botanische Zeitung,' and the ' Flora' for 1851, and 

 further in a letter from Dr. Merckliu to M. Schacht, which appeared 

 in the ' Liimsca ' at the close of last year. 



" He differs in a few subordinate particulars from M. Schacht, in 

 reference to the development and structure of the prothallium, or 

 pro-embryo, and of the antheridia and spiral filaments ; but these do 

 not require especial mention, except in reference to the vesicular end 

 of the spiral filament described by Schacht, which Mercklin regards 

 an a remnant of the parent vesicle, from which the filament had not 

 become quite freed. The observations referring to the so-called ovule, 

 and the supposed process of impregnation, are very important ; they 

 are as follows : 



" ' 1. The spiral filaments swarm round the ovule in numbers, fre- 

 quently returning to one and the same organ. 



" ' 2. They can penetrate into ovules. This was seen only three 

 times in the course of a whole year, and under different circumstances; 

 twice a spiral filament was seen to enter a still widely open young 

 ovule, then come to a state of rest, and after some time assume the 

 appearance of a shapeless mass of mucilage ; the third case of pene- 

 tration occurred in a fully developed ovule through its canal; it 

 therefore does not seem to afford evidence of the import of the spiral 

 filament, but certainly of the possibility of the penetration. 



" ' 3. In the tubular portion of the ovule, almost in every case, 

 peculiar club-shaped granular mucilaginous filaments occur at a 

 definite epoch ; these filaments, like the spiral filaments, acquiring a 

 brown colour with iodine. These mucilaginous bodies sometimes 

 exhibit a twisted aspect, an opaque nucleus, or a membranous layer, 

 peculiarities which seem to indicate the existence of an organisation. 



" ' 4. These club-shaped filaments are swollen at the lower capitate 

 extremity, and have been found in contact with the embryo-sac, or 

 globular cell, which forms the rudiment of the future frond. 



" ' 5. The spiral filaments, which cease to move and fall upon the 

 prothallium, are metamorphosed, become granular, and swell up.' 

 " Hence the author deduces the following conclusions : 

 " ' That these clavate filiform masses in the interior of the ovule 

 are transparent spiral filaments, which at an early period, while the 

 ovule was open, have penetrated into it; which leads to the pro- 

 bability that 



" ' 1. The spiral filaments must regularly penetrate into the ovules; 

 and 2. They probably contribute to the origin or development of the 

 young fruit frond (or embryo). In what way this happens the author 

 knows not, and the details on this point given by Suminski remain 

 unconfirmed fact*.' 



" An important point in this essay is the view the author takes of 

 the whole process of development in this case. He regards it as not 

 analogous to the impregnation in the Phanerogamia, since the essen- 

 tial fact is merely the development of a frond from one cell of the 

 prothallium, which he considers to be merely one of the changes of 

 the individual plant, while all the other authors who have written on 

 the subject, with the exception of Wigand, call the first frond, with 

 its bud and root, an Embryo, and regard it as a new individual ; or 

 at all events, even a distinct member of a series of forms, constituting 

 collectively the representatives of the species. 



" Finally, Hofmeister, in his notice of this essay in the ' Flora,' 

 declare* that the development of the so-called embryo, or first frond, 

 commences not by the subdivision of the globular cell, or embryo-sac, 

 but by the development of a free cell, or embryo vesicle in this, like 

 what occurs in the embryo-sac of the Phanerogamia ; and he asserts 

 that this is the first stage of development from the globular cell in 

 nil the vascular Cryptogams, including that found in the pistillidia 

 of the Mosses." 



The position of the Ferns in a natural system of classification has 

 not l>een a matter of much difference. Their imperfect organs of 



reproduction have at once led to their being placed by most botanists 

 among Cryptogamia ; nevertheless Bory St.-Vincent elevates Ferns to 

 ,he rank of a class intermediate between Monocotyledons and Acoty- 

 edons, or Cryptogamia ; at the same time he rejects the view of 

 Jussieu, who, from the mode of germination of their sporules, placed 

 ;he Ferns among the Monocotyledons. Their relation with the flower- 

 ing plants is seen through Cycadaceie, with which order they agree in 

 ;heir gyrate vernation and their pinnate leaves. Their affinity with 

 ^ryptogamic Plants is obvious in the Equisetacece and Lycopodiacece. 

 The order of Ferns may be divided into the following sub-orders, 

 which Lindley regards as of the rank and value of orders : 



I. GLEICHENIACE.E. The thecas with a transverse or obliquely trans- 

 verse complete elastic annulus or ring, bursting vertically. The species 

 are tropical, or extra-tropical only in the Southern Hemisphere, of a 

 harsh and rigid texture, simple or generally with copious dichotomous 

 branches and gemmse in the axils ; the ultimate branches pinnatifid. 

 None of the genera of this order, as understood by Hooker, are British. 

 It includes about forty species. 



II. PoLYpoDlACE.fi, with the sori dorsal, often near or at the margin, 

 various in form, sometimes constituting au uniform linear or spreading 

 mass, naked or furnished with an involucre, the thecte 1-celled, with 

 a longitudinal or oblique elastic articulated generally incomplete ring, 

 bursting transversely and irregularly. This is a very extensive sub- 

 order : the species inhabit almost every part of the world, from the 

 tropics to the arctic and antarctic regions ; they are exceedingly vari- 

 able in size and appearance, including the largest tree-ferns and the 

 smallest herbaceous species. It contains by far the largest number 

 of genera of any of the sub-orders of Ferns. Many of these are very 

 extensive, and have no British representatives, as Cyathea, Bemitelia, 

 Alsophila, Diclctonia, &c. 



III. OSMUNDACE.E has the thecco with an operculiform ring, or 

 without one, reticulated, striated with rays at the apex, bursting 

 lengthwise, and usually externally. The species of this sub-order are 

 not numerous. 



IV. DAN.SACE.E. The thecae sessile, without any ring, concrete 

 into multilocular sub-immersed masses, opening at the apex. This 

 is also a small sub-order, with three genera Daruea, Marattia, and 

 Kaulfuitia. 



V. OPHIOGLOSSACE.B. The thecns single, roundish, coriaceous, 

 opaque, without ring or cellular reticulation, half 2-valved, with a 

 straight vernation. It embraces the genera Op/tioglossmn, Jldimntho- 

 ttachyi, and Botrychium. 



The following is an arrangement of the British genera of Ferns : 



Sub-Order Polypodiacea. 

 Tribe Polypodita. The sori nearly circular, without an iudusium. 



Genera, A lloiorus, Polypodium, Woodtia. 

 Tribe A tpidiece. The sori nearly circular, covered by au indusium. 



Genera, Laatrea, Polystichum, Cystopterit. 

 Tribe Atplmiett. The sori oblong or linear, covered by an indusium 



opening longitudinally on one side. 

 Genera, Athyrium, Asplenium, Scolopendrium. 

 Tribe Grammitidece. The sori elongate, without an indusium. 



Genus, Ceterach. 



Tribe Adianlarife. The thecso covered by a marginal or sub-marginal 

 elongated part of the frond, or by a separated portion of the 

 cuticle, resembling an indusium. 

 Genera, Blechnum, Pteris, Adiantum. 



Tribe HymenophyUea:. The thecse opening irregularly ; the ring oblique, 

 eccentric, transverse, complete ; the receptacle terminating a vein 

 at the margin of the frond. 

 Genera, Trichoma.net, J/ymenophyllum, 



Sub-Order Oamundacere. 



Tribe Osmundece. The vernation circinate ; the rachis solid ; thethecro 

 stalked. 



Genus, Otmunda. 



Sub-Order Ophioyloiia,cea>. 



Genera, Opkioyloiswn, Botrychium. 



The Ferns have a wide geographical distribution. The herbaceous 

 and shrubby kind being found towards the north and south poles : 

 whilst the tree-ferns rival the gigantic palms in the forests of tropical 

 climates. It is these last which give a peculiar character to the 

 vegetation of the countries where they grow, as their foliage and stems 

 differ altogether from any that are observed amongst flowering plants. 

 The proportion which they bear to other plants varies much in 

 different parts of the world. In Jamaica they are in the proportion 

 of 1 to 9 ; in New Guinea as 28 to 122 ; in New Ireland as 13 to 60 ; 

 in the Sandwich Islands as 40 to 160; on continents they are less 

 numerous ; in equinoctial America 1 to 36 ; in Australia 1 to 37 ; in 

 France 1 to 63 ; in Portugal 1 to 116 ; in the Greek Archipelago 1 to 

 227 ; in Egypt 1 to 971. In the north their proportions are greater; 

 they form in Scotland 1 to 31 ; in Sweden 1 to 35 ; in Iceland 1 to 18 ; 

 in Greenland 1 to 10 ; and the North Cape 1 to 7. 



The properties and uses of the Ferns are not in proportion to their 

 numbers in the vegetable kingdom. Many of them deposit starch in 

 their rhizomatn, from which food may be prepared. The roots of 



