442 
VASCULAR CRYPTOGAMS. 
(c) AsplenksR. The sori are unilateral on the course of the veins, and are covered 
by a lateral indusium, or rarely without any ; or they extend at their apex over the 
back of the veins, and are covered by an indusium springing from it ; or they occupy 
special anastomosing branches of the veins, and are unilateral and covered by an indusium 
free on the side of the vein. [Asplenium, Scolopendrium.) 
(d) Aspidiese. The sori are dorsal on the veins, covered with an indusium, or ter- 
minal and without indusium. {Aspidium.) 
(e) Da'valliece. The sori are terminal on a vein or at a fork, and are furnished with 
an indusium ; or are placed on an intramarginal anastomosing bend of the veins, and 
covered with a cup-shaped indusium, free at the outer margin. {Da'vallia, Nepbrolepis.) 
(f) Pteridex. The sori are continuous along the margin of the leaf, and are covered 
by a false indusium. {Pteris^ Adiantum, Blechnum.) 
Order III. RHIZ0CARPE^^ 
The Sexual Generation (Oophore) of Rhizocarps is developed from spores 
of two different kinds ; the smaller spores {niicrospores) produce antherozoids, 
and are therefore male ; the larger spores {?Jiacrospores), which exceed the smaller 
kind several hundred times in size, produce a small prothallium, which never 
separates from them, and forms one or several archegonia; the macrospores may 
therefore be considered to be female. 
The development of the antherozoids is preceded by the formation of a very 
rudimentary Alale Prothallium. In the genus Salvinia the microspores lie imbedded 
in a mass of granular hardened mucilage (as they do also in Azolla, in which plant 
their germination is not known), which fdls up the whole of the microsporangium ; 
they do not escape, but the endospore of each of them grows out into a tube 
which pierces the mucilage and the wall of the sporangium and forms a septum at 
its curved end (Fig. 309, ^ and B). The terminal cell of the tube thus produced 
is again divided by an obhque wall, after which the protoplasm contracts in the two 
cells (which Pringsheim together calls the antheridium), and splits up by repeated 
bipartition into four roundish primordial cells, each of which forms an antherozoid. 
In addition a small portion of the contents remains inactive in each of the two 
cells. The antheridial cells burst by transverse shts to allow the escape of the 
antherozoids. The spirally-coiled antherozoid is still enclosed for a time in its 
^ G. W. Bischoff, Die Rhizocarpeen u. Lycopodiaceen (Nürnberg 1828). — Hofmeister, Vergleich. 
Untersuch, 1851, p. 103. — [On the Germination, Development, and Fructification of the Higher 
Cryptogams, Ray Soc. 1862, pp. 318-335.] — Ditto, Ueber die Keimung der Salvinia natatis (Abhand. 
der königl. Sachs. Gesellsch. der Wissensch. 1857, p. 665). — Pringsheim, Zur Morphologie der Sal- 
vinia natans (Jahrb. für wissensch. Bot. vol. IH. 1863). — J. Hanstein, Ueber eine neuholländische 
Marsilia (Monatsber. der Berliner Akad. 1862, Ann. des Sei. Nat. 4th series, vol. XX, 1863, pp. 149- 
166).— Ditto, Befruchtung u. Entwickelung der Gattung Mnrs/Zm (Jahrb. für wissensch. Bot. vol. IV, 
1865). — Ditto, Pilularise globuliferse generalio, cum Marsilia coraparata (Bonn 1866). — Nägeli u. 
Leitgeb, Ueber Entstehung u. Wachsthum der Wurzeln bei den Gefässkryptogamen (Berichte der 
bayer. Akad. der W^issensch. 1866, Dec. 15, and Nägeli's Beiträge zur wissensch. Bot. vol. IV. 1867). 
— Millardet, Le Prothallium male des Cryptogames vasculaires (Strasbourg 1869). — A. Braun, 
Ueber Marsilia u. Pihilaria (Monatsber, der königl. Akad. der Wissensch. Berlin, Aug. 1870). — 
E. Russow, Histologie u. Entwickelung der Sporenfrucht von Marsilia (Dorpat 1871). — Strasburger, 
Ueber Azolla (Jena 1873). — Juranyi, Über die Entwickelung der Sporangien und Sporen von Salvinia 
natans (Berlin 1873), — [Arcangeli, Sulla Pilularia globnlifera e suWa. Salvinia natans; Nuov, Giorn. 
Bot. Ital. 1876.] 
