‘4 
REPRODUCTION OF MARSILEACEX AND SELAGINELLACES. 833 
productive organs of this order are generally distinguished as 
microsporangia, (figs. 818 and 820, a), and macrosporangia or 
megasporangia (fig. 820, b). These two structures are either 
contained in separate sacs, as in Salvinia (fig. 820), or in the 
same, asin Marsilea (fig. 817). The microsporangia or anthe- 
ridia contain a number of small cells, called generally micro- 
spores or small spores ( fig. 818), which ultimately pr oduce anther- 
ozoids remarkable for their length and delicacy (fig. 1153). The 
macrosporangia (jig. 820, b) contain commonly but one spore, 
called an ovulary spore, large spore, mccrospore, or megaspore. 
In their organs of fructification the plants of this order closely 
resemble the Selaginellacez. Like the Selaginellacex, the large 
spores also produce a small prothallium confluent with them 
(fig. 1154), in which subsequently only a single archegonium 
generally, as in Piluwlaria and Marsilea, appears (jig. 1154, «), 
although in Salvinia several archegonia are formed.  Fertili- 
Bre. 1 153. Fie. 1154. 
THE 
@ 9'O 
Fig. 1153. Small spore or microspore, of Pill-wort (Pilularia globuliferc ), 
bursting and discharging small cells enclosing antherozoids. Some 
of the latter may be observed to have escaped by the rupture of the 
small cells in which they were contained. Fig. 1154. Vertical section 
of the prothallium of the above, which is formed, as in the Selaginellacex, 
in the interior of the large spore or macrospore. Only one archegonium, 
a,is here produced in the centre. Thearchegonium consists of an inter- 
cellular canal, leading into a sac below, in which may be seen a solitary 
germ or embryonal cell. 
sation takes place by the contact of the antherozoids with the 
germn-cell of the archegonium, which immediately developes, 
and forms a pseudo-embryo bearing a great apparent similarity 
to the embryo of a monocotyledon, from which a leafy stem 
bearing fructification is ultimately produced. 
(4) Selaginellaceex or Selaginellas.—The two reproductive 
organs of this order are usually termed macrosporangia or mega- 
sporangia (figs. 813 and 816), which represent the female ; 
and microsporangia or antheridia (figs. 814 and 815), which are 
regarded as male organs. The contents of the microsporangia, 
are called small spores or microspores, which break up into two 
sets of cells—one of which remains inactive, and probably re- 
presents an abortive prothallium ; while the other developes 
the antherozoids (fig. 1155, c). In the macrosporangia are formed 
large spores, macrospores, or megaspores (fiy. 816). 
It is not till some months after being sown that the spores 
3H 
