374 
MUS CI NE 
in this group acts like an apical cell, giving rise by a series of longitudinal divisions 
to several tiers of cells, each tier consisting of three external cells and an internal 
canal-cell and in other respects resembling the single tier of neck-cells formed in 
the Liverworts. In this way a long and subsequently twisted neck is formed, 
consisting of six external rows of cells investing the central row of canal-cells. 
Below, the cells forming the neck become continuous with the wall of the ventral 
portion of the archegonium, which consists usually of two (four in Sphagnuvi) layers 
of cells. The central cell, which makes 
its appearance here earlier than in the 
Liverworts, becomes divided by a trans- 
verse wall into an upper cell, the ventral 
canal-cell, and a lower cell, the proto- 
plasm of which contracts and forms the 
oosphere (Fig. 256, B). The conversion 
into mucilage of the canal-cells and the 
opening of the neck take place in the 
same manner as in the Liverworts. 
The Sporogonium^ which results from 
the fertilised oosphere, attains, in Sphag- 
7ium, almost perfect development within 
the actively growing ventral portion of the 
archegonium, which becomes transformed 
into the calyptra ; but in all other Mosses 
the calyptra is torn away from the vagi- 
nula at its base, by the elongation of the 
sporogonium, usually long before the de- 
velopment of the spore-capsule, and (ex- 
cept in Archidiiim and its allies) is raised 
up as a cap. The neck of the arche- 
gonium, the walls of which assume a deep 
red-brovv'n colour, still for some time 
crowns the apex of the calyptra. The 
sporogonium of all Mosses consists of a 
stalk (the Seid), and the spore-capsule 
( Theca or Urn) ; but the former is very 
short in Sphagnum, Andrecea, and Archi- 
dium, longer in most other genera, and with its base planted in the tissue of 
the stem, which, after fertiHsation, grows luxuriantly beneath and around the 
archegonium, forming a sheathlike investment, the Vaginula. The unfertilised 
archegonia may frequently be seen on the exterior slope of the vaginula, since 
only one archegonium is usually fertilised in the same receptacle, or it is only 
in the one first fertilised that an embryo is developed. The capsule has in 
all Mosses a wall consisting of several layers of cells and a distinct epidermis which 
sometimes possesses stomata^; the whole of the inner tissue is never used up in 
^ The stomata upon the capsules of Mosses are peculiar, as Schimper has shown, in that the 
mother-cell of a stoma is not divided into two guard- cells, for the dividing wall docs not extend 
Fig. 257. — Fimaria hyg)'0)net>-ica ; A orig'in of the sporo- 
gonium f f in the ventral portion b b of the archegonium 
(longitudinal section X Soo) ; B, C different further stages of 
development of tlie sporogoniumyand of the calyptra <r; h neck 
of the archegonium (x about 40). 
