FERNS. 



[ 322 ] 



FIBRINE. 



Fig. 240. 



the protliallium, other cellular bodies, of 

 more complex structure, which are the 

 (trchegoma or ovule-like bodies. The arche- 

 goniuin consists of a cellular papilla, com- 

 posed of a few colourless cells, with a canal 

 running- down its centre (an intercellular 

 passage), leading to a cell (embryo-cell) at 

 the bottom, contained in a cavity (embryo- 

 sac) in the substance of the prothalliuin. 

 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 prothal- 

 lium, which decays away, and grows up 

 into the ordinary leaf-bearing 

 stern of the Ferns (fig. 240). 

 The prothallia bear a vari- 

 able number of archegonia, 

 but not nearly so many as of 

 antheridia ; 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 Pteris, seedling, 

 bounding their cavities. 



The characters of the prothallium of the 

 Ophioglossacece 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 Polypodiaceae. 



The Ferns produce also gemmce on the 

 leaves of full-grown plants; and even the 

 prothallia are capable of vegetative mul- 

 tiplication ; for 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 innovations usually bear 

 antheridia alone, and not archegonia. 

 The Ferns are divided into six orders. 

 GLEICHENIACEJE. Sori dorsal, of few 

 thecee, naked ; thecae opening vertically by 

 a broad transverse complete annulus. 



POLYPODIACEJE. Sori dorsal or margi- 

 nal, subglobose ; thecae numerous, with 01 



without an indusium, usually stalked, more 

 or less completely surrounded by a vertical 

 annulus, and bursting transversely (except 

 in Hymenophylleae). 



OSMUNDACE.E. Thecse two-valved, open- 

 ing across the apex, with a short horizontal 

 annulus ; vernation circinate. 



SCHIZ^ACE^E. Thecae two-valved, open- 

 ing down the side, crowned by a complete 

 operculiform annulus ; vernation circinate. 



MABATTIACKSB. Thecae opening by a 

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

 lus, usually united into concrete masses 

 (synangia) ; vernation circinate. 



OPHIOGLOSSACECE. Thecae deeply two- 

 valved, opening down the side nearly to 

 the base ; no aunulus ; vernation erect. 



BIBL. Berkeley, Crypt. Hot. 507 ; Presl, 

 Pteridograph. 1838;Payen,J?or5. Cryptogam. 

 1850; Biachoff,Kryptoffam. Gewacfae,182&; 

 Mohl, Martins' a Plant. Cryptog. Brasil. ; 

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

 Newmtai^Br.Ferns Henfrey, Devel. of Ferns 

 from Spores, Linn. 2Vww.xxi.117, 1853 ; Re- 

 product, of Cryptogamia, Ann. N. H. 1852 ; 

 Hofmeister, Entwickelung, Scichs. Ges. 1857, 

 v. ; JReess, Jahr, wiss. Bot. v. I860 ; Stras- 

 burger, Befruchtung, Jahr. wiss. Bot. 1809, 

 vii. 390 j Kny, Monatsb. Berl. Akad. 1809 ; 

 id., Jahr. wiss. But. vii, 1 j Janczewsky, Bot. 

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

 Syn. Filic. (figs, of all gen. and description of 

 all species} ; Kny, Ann. N. H. 1870, v. 233 ; 

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

 Filic. 1875; Waldner, Ferns of Germany, 

 1880 ; Blair, European Ferns, 1881. 



FIBRINE. Fibrine exhibits very nume- 

 rous line fibres ; and is soluble in, or rendered 

 so transparent by acetic acid, as to be 

 invisible. Its chemical relation to the 

 other proteine-corupounds 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 minute granules of fat. 



Fibrine is coloured by the test-liquids of 

 Millon and Pettenkofer. 



According to Schmidt's experiments, 

 fibrine does not pre-exist in blood, but is 

 formed by the chemical combination of 

 a fibrinogenous 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 



