REPRODUCTIVE ORGANS OF SELAGINELLACES. 369 
The sporangia are somewhat reniform, two-valved cases 
closely resembling the antheridium or microsporangiwm of the 
Selaginellaceze, and containing a number of spores, the smaller 
of which ultimately contain antherozoids (see Selaginellacez). 
But little is known of the early development of the spores, but 
they ultimately produce large prothallia, with root-hairs like the 
Filices, and like them these prothallia are moncecious, bearing 
antheridia and archegonia on their upper surface, and from the 
sexual action of which new plants are formed. Hence the 
Lycopodiacez, like the Filices and Equisetacez, also exhibit an 
example of alternation of generations. 
4. SELAGINELLACEZ OR SELAGINELLAS.—The sporangia or 
capsules in the plants of this order are situated in the axils or at 
Fie 813. Fig. 814. Fic. 815. 
Fic. 816. 
Fig. 813. Scale or leaf of Selaginella apoda, with macrosporangium in its 
axil.—Fig. 814. Antheridium or microsporangium of the above, placed 
in the axil of a leaf or scale. After Henfrey—Ffig. 815. Microsporan- 
gium of a species of Selaginella. It is two-valved, and contains a number 
of small spores or microspores. Fig. 816. Macrosporangium or mega- 
sporangium of a species of Selaginella. This is atwo-valved, four-lobed sac, 
and contains four large spores which are commonly called macrospores. 
the base of the leaves (jigs. 815 and 814). The leaves thus 
bearing the fructification are frequently collected together into 
a kind of cone or spike, while at other times they are scattered 
along the stem. The spores, like those of the Marsileacex, are 
of two kinds (heterosporous), and are enclosed in separate cases. 
These cases are variously named ; the names which would corre- 
spond to those commonly used in describing the Marsileacez 
would be sporangia and antheridia ; but the former are also 
more frequently called megasporangia or macrosporangia (figs. 
813 and 816), and the latter microsporangia (figs. 814 and 815). 
The contents of the former are generally termed large spores, 
megaspores, or macrospores (fig. 816); and those of the latter 
small spores or microspores (fig. 815). FE 
The megasporangia or macrosporangia are usually two-valved 
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