^.00 VASCULAR CRYPTOGAMS. 



their outer gelatinous envelope, which surrounds the exospore, swelling up. Their 

 size being thus increased, they glide out, and escape into the surrounding water, where 

 the germination of Marsilea sal-vatrix begins and completes its course with extraordinary 

 rapidity. With a favourable summer temperature, antherozoids and archegonia ready 

 for fertilisation are formed within 12 or 18 hours. Hanstein was the first to de- 

 scribe these processes accurately ; I have myself repeatedly seen them in sporocarps, 

 for which I am indebted to him^ To him also we owe the knowledge of a similar 

 though in many respects different process in Pilularia glohuUfera. In this species the 

 sporocarps lie on or beneath the ground ; they burst at the apex into four lobes, and 

 exude a tough hyaline mucilage which escapes only w^hen the sporocarp is buried in the 

 earth, forming a round drop which continues to increase in size for some days. In this 

 drop of mucilage the macrospores and microspores rise to the surface and germinate, the 

 drop of mucilage melting away only after fertilisation has been accomplished. The 

 fertilised macrospores remain lying on the ground, and are temporarily fixed to it by the 

 root-hairs of the prothallium, until the first true roots of the young plant penetrate 

 into the ground. 



CLASS X. 



LYCOPODIACEyEl 



The Sexual Generatmi of Lycopodiaceae is, up to the present time, known 

 only in the genera Isoetes and Selaginella; in these large female and small male 

 spores are produced, as in the Rhizocarpese. In the genus Lycopodium only the 

 early stages of germination are known, and that only in one species; Hke 

 Tmesipteris and Psilotum, it possesses only one kind of spore, which corresponds 

 externally to the microspores of the first-named general These differences would 



' [See Hanstein in Ann. des Sci. Nat. 1863, vol. XX, pp. 149-166.— Ed.] 



2 Hofmeister, Vergleichende Untersuchungen, 185 1. — [Germination, Development, and Fructifi- 

 cation of the Higher Cryptogamia, Ray Soc. pp. 336-399.] — Mettenius, Filices horti bot., Lips. 1856. 

 — Cramer, Ueber Lycopodium Selago in Niigeli and Cramer's Pffanzen-phys. Unters. Heft 3, 1855. — 

 Hofmeister, Entwickelung der Isoetes lacustris in Abhandl. der konigl. Sachs Gesellsch. der Wis- 

 sensch. vol. IV, 1855. — De Bary, Ueber die Keimung der Lycopodiaceen, in Berichte der naturf. 

 Gesellsch. zu Freiburg-in-Br. 1858, Heft IV.— N:igeli u. Leitgeb, Ueber Entstehung u. Wachsthum 

 der Wurzeln, in Nageh's Beitrage zur wissensch. Bot. Heft IV, 1867. — A. Braun, Ueber Isoetes in 

 Monatsber. der Berl. Akad. 1863.— Milde, Filices Europe et Atlantidis, Leipzig 1867. — Mettenius, 

 Ueber Phylloglossum, Bot. Zeitg. 1867. — Millardet, Le prothallium male des crypt ogames vascu- 

 laires, Strassburg 1869.— Juranyi, Ueber Psilotum, Bot. Zeitg. 1871, p. 180. — Pfeffer, Entwickelung 

 des Keims der Gattung Selaginella in Planstein's Botanische Abhandlungen, Heft IV, 187 1. 



3 [J. Fankhauser (Bot. Zeitg. 1873, pp. 1-6) has described the hitherto unknown prothallium of 

 Lycopodium, which is underground and destitute of chlorophyll. In September he found it more or 

 less preserved and still attached to young plants less than three inches high, growing in moss in a 

 damp wooded locality near Langenau in Emmenthal. He describes it as a yellowish white irregu- 

 larly lobed structure, furnished sparingly with small root-hairs. The under side is comparatively 



