FERNS. 



[ 322 ] 



FIBRINE. 



Fio-. 240. 



the protliallium, other cellular bodies, of 

 more complex structure, which are the 

 archeijonia or ovule-like bodies. The arclie- 

 goiiiuui consists of a cellular papilla, com- 

 posed of a few colourless cells, with a caual 

 running down its centre (an intercellular 

 passage) leading to a cell {emhnjo-ceU) at 

 the b.jttom, contained in a cavity {Pinhri/o- 

 sac) in the substance of the prothalliuui. 

 The ciliated spiral filaments make their way 

 down this canal, like the pollen-tubes 

 through the micropyles of Phanerogamous 

 ovules ; and then the embryo-cell becomes 

 developed into an embryo, which soon 

 exhibits rudimentary leaves and rootlets, 

 bursts out from the cavity of the protlial- 

 lium, which decays away, and grows up 

 into the ordinary leaf-bearing 

 stem of the Ferns (fig. 240). 

 The prothallia bear a vari- 

 able number of archegonia, 

 but not nearly so many as of 

 authcridia ; and they exhibit, 

 in most fully-developed spe- 

 cimens, a number of effete 

 organs of both kinds, which 

 are readily distinguished by 

 the deep-brown colour as- 

 sumed by the membranes 

 bounding their cavities. 



The characters of the prothallium of the 

 Ophior/lossaceci' differ somewhat from the or- 

 dinary forms : the prothallium is developed 

 in the soil, several inches below the surface, 

 and is of a whitish-yellow colour internally, 

 being destitute of chlorophyll and starch ; 

 its external surface is brown. The anthe- 

 ridia are chiefly produced upon the upper 

 side, the archegonia below, both immersed 

 in the substance of the prothallium. The 

 spermatozoids are described as being larger 

 than in Polypodiacete. 



The Ferns produce also (jemmce on the 

 leaves of full-grown plants; and even the 

 prothallia are capable of vegetative mul- 

 tiplication ; f )r if their archegonia are all 

 abortive, they go on vegetating for a long 

 time, and produce new prothallia, by some 

 of their marginal cells budding out and re- 

 peating the original mode of growth of the 

 spore itself. These innovatioits usually bear 

 antheridia alone, and not archegonia. 

 The Ferns are divided into six orders. 

 Gleiciieniace^I':. Sori dorsal, of few 

 thecpe, naked ; theca) opening vertically by 

 a broad transverse complete annulus. 



Poi.Yi'OT)iACE.i3. Sori dor.-al or mnrpi- 



Pteris, seedlin" 



nal, 



subglobose ; 



tliecse numerous, with or 



without an indusium, usually stalked, more 

 or less completely surrounded by a vertical 

 annulus, and bursting transversely (except 

 in Hymjnophylleai). 



OsMUNDACE^. Thecsetwo-valved, open- 

 ing across the apex, with a short horizontal 

 annulus; vernation circinate. 



ScHiz^ACE.E. Thecfe two-valved, open- 

 ing down the side, crowned bv a complete 

 operculiform annulus ; vernation circinate. 



MARATriACE.E. Thccps opening by a 

 lateral slit or a pore at the apex ; no annu- 

 lus, usually united into concrete masses 

 (synangia) ; vernation circinate. 



Ophioglossace.e. — Tliecse deeply two- 

 valved, opening down the side nearlv to 

 the base ; no annulus ; vernation erect. 



BiBL. Berkeley, Crypt. Bot. 507 ; Presl, 

 Pteridof/raph. IS-'jtj; I'ayen, Z?o^. Cryptoc/am. 

 1850; iMrichoitKniptoyam. Getrdc/ise, 1828; 

 Mohl, Martinson I'lunt. Cryptoy. Brasil. ; 

 Moore, Index Filicum & Handb. of Br. Ferns ; 

 Newman,i)r.i^ftrwA'; Henf rev, D^re/. of Ferns 

 from Spores, Linn. Tr a ns.xxi. 117, 18*53 ; He- 

 product, of Cryptoyajnia, Ann. N. II. 1852 ; 

 Ilofmeister, Entuickehiiiy, Sachs. Ges. 1857, 

 v. ; Reess, Jnltr, wiss. Bot. v. 1866 ; Stras- 

 burger, Bcfruchfunq, Ja/ir. unss. Bot. 1869, 

 vii. 390 ; Kny, Mmafsh. Berl. Aknd. 1869 ; 

 id., Jahr. wiss. Bot. A'ii. 1 ; Janczewsky, Bot. 

 Zeit. 1872,418; Sachs, Bot. 415; Hooker, 

 Syn. Filic. (fiys. of all yen. and description of 

 all species) ; Kny, Ann. N. II. 1870, v. 233 ; 

 Strasburger, ibid. 1870, v. 331 ; Smith, Hist. 

 Filic. 1875 ; "V^'aldner, Ferns of Germany, 

 1880 ; Blair, European Ferns, 1881. 



FIBRINE. — Fibrine exhibits very nume- 

 rous fine fibres ; and is soluble in, or rendered 

 so transparent by acetic acid, as to be 

 invisible. Its chemical relation to the 

 other proteine-compovmds has not been 

 satisfactorily determined. A substance re- 

 sembling fibrine in many of its characters, 

 if not identical with it, occurs upon the 

 surfaces of inflamed membranes, &c. ; in 

 these cases it generally includes the other 

 elements of inflammation, and almost al- 

 ways a number of mimite granules of fat. 



Fibrine is coloured by the test-liquids of 

 Millon and Pettenlcofer. 



According to Schmidt's experiments, 

 fibrine does not pre-exist in blood, but is 

 formed by the chemical combination of 

 a fibrinogenons substance occurring in the 

 blood-plasma with a fibrino-plastic matter 

 contained in the blood-corpuscles, which 

 escapes from them ; more recently, Schmidt 

 considers the separation of fibrine to depend 



