ris’ { 
‘ 300 i) WaetPal oe Ph stg Baton 
a non The fidiment of this organ is first of all siitrounceean * aan 
by a cell-wall, and then gradually developes—under the _ : 
shelter of the archegonium, which grows with it and which — a be 
is from this time called the calyptra—and developes into 
_-the stalked sporogonium. ‘The sporogonium does not any- _ 
where unite in its growth with the vegetative structure, even — 
when its pedicel penetrates into its tissue. When mature, | 
the sporogonium, elevated by the sudden and rapid increase 
in length of the pedicel or se¢a, ruptures the ca'yptra, opens, 
and allows the escape of a great number of spores. As 
a rule, several archegonia are grouped together; but it is 
very rare that more than one matures, the rest being abor- 
tive. In some genera the archegonium is surrounded in 
addition by a so-called ‘ calyx’ [or perichetium|, consisting 
of several connate leaves. In the sporogonia of the Hepa-- 
tice there usually occur, in addition to the spores, also 
pecuhar elongated cells termed eafers, furnished with a 
brown spiral band, which is sometimes simple, as in frul- 
fania, sometimes double (Fig. 422 It1.). Rarely, as", 
_“Anthoceros, a row of cells or columella remains in addition 
in the axis of the sporogonium (Fig. 421). The sporo- 
gonium usually opens with four, in Axthoceros with two 
valves ; in the Ricciez it bursts irregularly. On germina- | 
tion the spore first puts out an irregular, often filiform, struc- © 
ture, the pro-embryo, on which the bud is produced from | 
which the young plant arises. ‘The course of development 
of the Hepaticze shows a clearly marked alternation of 
~ 
~ 
generations. ‘The first (sexual) generation begins with the. — 4 
germinating spore, and closes with the act of fertilisation; =~ 
_ the second (asexual) generation consists of the sporogonium. 
eve ah © ae Z, 4 on 
The Hepaticze are classified into four families :— 
ty | 3. Riccir#. The thallus is expanded flat and floats 1 in water ; 3 ae : 
aie sporogenium,is imbedded in the thallus, and does not project above it 5 
it dehisces irregularly, and contains uo elaters. ‘i 
2. ANTHOCEROTE. . The thallus is expanded flat ; ite cata a aS 
