FILICINEM. 421 



Order II. Filices\ 



The Sexual Generation (Oophore) or Prothallium of Ferns is a thalloid body- 

 containing chlorophyll and obtaining its nourishment independently; its development 

 presents striking resemblances to that of the simpler Hepaticae, and to a certain 

 extent even to the formation of the protonema of some Mosses. It produces simple 

 tubular unarticulated root-hairs, and finally antheridia and archegonia. Its develop- 

 ment and the duration of its life may embrace a considerable space of time, espe- 

 cially when the archegonia are not fertilised. 



When the spores germinate, which usually does not take place till a con- 

 siderable time" after dissemination (but in Osmunda after only a few days), the cuti- 

 cularised exospore, generally provided with ridges, bosses, spines, or granulations, 

 spHts along its edges ; the endospore, which now protrudes and is not unfrequendy 

 already divided by septa, produces the prothallium, either immediately, as in 

 Osmunda, or after the preliminary formation of a filamentous protonema, which 

 presents in Hymenophyllaceae certain resemblances to that of the Andreseaceae and 

 of Tctraphis among Mosses. The development of the prothallium has been more 

 exactly investigated only in the Hymenophyllacese, the Polypodiacese, and also in 

 Osmunda and Aneimia'^ ; and the considerable differences which have thus been 

 established necessitate separate descriptions. 



In the Hymenophyllaceae the contents of the spore are divided, even before 

 germination, into three cells meeting in the centre ; in some species of Trichomanes 

 small cells are cut off at three points of the circumference, while a large central 



^ H. von Mohl, Ueber den Ban des Stammes der Baumfarne (Verm. Schriften, p. 108). — Hof- 

 meister, Ueber Entwickelung und Bau der Vegetationsorgane der Fame (Abhandlungen der konigl. 

 Sachs. Gesells. der Wissen. 1857, vol. V). — Ditto, Ueber die Verzweigung der Fame (Jahrb. fiir 

 wissen. Bot, vol. III. p. 278). — Mettenius, Filices Hort. Bot. Lipsiensis (Leipzig 1856). — Ditto, Ueber 

 die Hymenophyllaceen (Abhandlungen der konigl. Sachs. Ges. der Wissen. 1864, vol. VII;. — Wigand, 

 Botanische Untersuchungen (Braunschweig 1854). — [On the Germination, Development, and Fruc- 

 tification of the Higher Cryptogamia, &c. Ray Society, 1862, pp. 128-266.] — Dippel, Ueber den 

 Bau der Fibrovasalstrange, in the Berichte deutscher Naturforscher u. Aerzte in Giessen, 1865, 

 p. 142. — Reess, Entwickelung des Polypodiaceensporangiums (Jahrb. fur wissen, Bot. 1866, vol. V. 

 p. 5). — Leszczyc-Suminski, Zur Entwickelungsgeschichte der Farnkrauter, 1848. — Strasburger, 

 Befruchtung der Farnkrauter (Jahrb. fiir wissen. Bot. 1869, vol. VII. p. 390). — Kny, Ueber 

 Entwickelung des Prothalliums und der Geschlechtsorgane, in the Sitzungsberichte der Gesellschaft 

 naturforschender Freunde in Berlin, Jan. 21 and Nov. 17, 1868. — Kny, Ueber Bau und Entwickelung 

 des Farnantheridiums (Monatsberichte der kais. Akad. der Wissen. Berlin, May 1869). — Kny, 

 Beitrage zur Entwickelungsgeschichte der Farnkrauter (Jahrb, fiir wissen. Bot. vol. VII. p. i). — • 

 Russow, Vergl. Unters. Petersburg 1872. — Janczewski, Ueber die Archegonien. Bot. Zeit. 1872, p. 

 418. — [On the development of the prothallium, see also Bauke, Keimungsgeschiche der Schizseaceen, 

 Jahrb. f. wiss. Bot. XI ; Burck, Develop, du prothalle des Aneimia, Arch. Neerlandaises, X ; Bauke, 

 Entwick. d. Prothalliums bei den Cyatheaceen, Jahrb. f. wiss. Bot. X ; Goebel, Entwick. d. Prothal- 

 liums von Gymno gramme leptophylla, Bot. Zeit. 1877; Janczewski et Rostafinski, Le prothalle de 

 V Hymenophyllum Tunbridgense, Mem. soc. nat. d. sci. natur. de Cherbourg, XIX ; Prantl, Die 

 Hymenophyllaceen, 1875.] 



^ Although the Osmundacese, Schizseacese, and Gleicheniaceec probably constitute a group apart 

 from the Polypodiacese and Hymenophyllacese, I introduce here what little is known concerning them, 

 for our knowledge is not sufficient to permit of any but an imperfect account of them being given. 

 Where it is not expressly stated to be otherwise, the descriptions given above refer to the Polypodiacese 

 and Cyatheacese. 



