FERNS. 



[ 259 ] 



FERNS. 



5 laced by most authors in the Animal King- 

 om, among the Infusoria, but with no satis- 

 factory character by which they can be dis- 

 tinguished from many vegetable organisms, 

 and differing from animals in their behaviour 

 with potash. (See VIBRIO.) These creatures 

 appear in myriads during the decomposition 

 which takes place when a piece of meat, &c., 

 slices of potato, fleshy Fungi, &c., are kept 

 moist and exposed to the air for some days 

 in warm weather; and they continue to multi- 

 ply until the putrefaction is complete, when 

 they die away. It is a question perhaps 

 whether these organisms liberate the ammo- 

 nia and carbonic acid by a kind of respiration 

 while living, or as an excrement, or whether 

 these gases result from the decay of the dead 

 individuals. These points require much fur- 

 ther investigation. 



One point of interest connected with the 

 fermentation-plants must not be passed over, 

 viz. that the supposed distinction between 

 the chemical processes of nutrition in ani- 

 mals and plants, falls to the ground when 

 these Fungi are taken into consideration, as 

 they do not live by converting inorganic 

 substances into organic compounds, but, like 

 animals, decompose ready-formed organic 

 compounds into others and into their inor- 

 ganic elements. 



The cause of the presence of these living 

 creatures in decomposing substances was 

 formerly referred to an autonomous produc- 

 tion of them, but this idea is not entertained 

 now. (See GENERATION, SPONTANEOUS.) 

 The whole question of fermentation is in 

 an unsatisfactory state, which must be the 

 excuse for this imperfect notice, especially 

 as it would be to go beyond our sphere to 

 enter upon the chemical theories of contact, 

 &c., and the analogous decompositions oc- 

 curring either evidently or apparently with- 

 out the production of independent micro- 

 scopic organisms. 



BIBL. Mulder, Chemistry of Veg. and 

 Anim. Phys. Fromberg's transl. 1849. p. 42; 

 Gmelin, Handbook of Organic Chemistry, 

 Lowig, Chemie der Organ. Verb. i. p. 223 ; 

 Turpin, Mcmoires; Mitscherlich, Poggend. 

 Annal. Iv. p. 224, Lehrbuch, 4 ed. p. 371, 

 Bericht. Berlin Akad. ; Cagniard Latour, 

 Poggen. Annal. xli. p. 193; Schwann, ibid. 

 p.184; \Jre,Biblioth. Univers. Genev. 1839; 

 Helmholtz, Mutter's Archiv, 1843. p. 453 ; 

 Boutron and Fremy, Erdm. and Marchand 

 Journ. xxiv. p. 364. See also under TORULA 

 and PENICILLIUM. 



FERNS. This class of Flowerless Plants 



offers very many points of interest to the mi- 

 croscopist, and indeed the use of magnifying 

 instruments is indispensable in their exami- 

 nation for botanical purposes. The Ferns 

 are characterized by the position of their 

 spore-cases or fruits, which are collected into 

 what to the naked eye look like streaks, spots, 

 or patches of a brown colour (sori) at the 

 back or lower surface of the leaves (fig. 225), 



Fig. 225. 



Scolopendrum vulgare. 



Nat. size. 



or at their margins ; these fertile leaves 

 either resembling the rest, or being modified 

 in a manner which more or less disguises 

 their nature, as in what are miscalled ' flow- 

 ering Ferns' (Osmunda (figs. 226 & 227), 

 Botrychium, &c.). 



The Ferns possess a stem which is more 

 or less developed in different cases ; in our 

 native kinds it is either a slender, horizontal, 

 subterraneous rhizome or rootstock, or a 

 thick, short, erect one, rising little above the 

 ground ; but in foreign kinds this erect stem 

 attains the form and dimensions of a tree, 

 growing up into a tall unbranched columnar 

 stem, sometimes more than fifty feet high. 

 The anatomical structure of the stem of the 

 Ferns is peculiar and special, depending on 



s2 



