324 



MUSCINEM. 



(3) The Sporogonium, which results from the fertilised oosphere, attains, in 

 Sphagnum, 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 vaginula at its base, by the elongation of the 

 sporogonium, usually long before the development of the spore-capsule, and (except 

 in Archidium and its allies) is raised up as a cap. The neck of the archegonium, 

 the walls of which assume a deep red-brown colour, still for some time crowns the 

 apex of the calyptra. The sporogonium of all Mosses consists of a stalk (the Seta)^ 



and the spore-capsule {Theca or Urn); 

 but the former is very short in Sphagnum, 

 Andreaea, and Archidium, longer in most 

 other genera, and with its base planted in 

 the tissue of the stem, which, after ferti- 

 lisation, grows luxuriantly beneath and 

 beside the archegonium, forming a sheath- 

 like protection, the Vagmida. The un- 

 fertilised archegonia may frequently be 

 seen on the exterior slope of the vagi- 

 nula, since only one archegonium is usu- 

 ally fertilised in the same flower, or it is 

 only the one first fertilised that perfects 

 its oospore. The capsule has in all 

 Mosses a wall consisting of several layers 

 of cells with a distinct epidermis which 

 sometimes possesses stomata; the whole 

 of the inner tissue is never used up in the 

 formation of spores, even when, as in 

 Archidium, it is subsequently supplanted 

 by them ; a large part of the central tissue 

 remains as the so-called Columella, and it 

 is at the circumference of this that the 

 mother-cells of the spores are formed. The 

 structure of the mature capsule, and espe- 

 cially the contrivances for dispersing the 

 spores, are, however, so different in the 

 various principal sections of Mosses that 

 it will be better to consider them more 

 closely separately, and the more so because by this means we shall at the same 

 time arrive at the distinctive characters of the larger natural systematic groups. 



In the mode of origin of the sporogonium there is, as might be expected, 

 less variety. The oospore is first of all clothed with a cell-wall, continues to grow 

 considerably, and is then divided by a (horizontal ? or) slightly inclined wall. 

 Hofmeister asserts that in Bryum argenteum the upper cell (that facing the neck 

 of the archegonium) is again divided once or twice by horizontal septa before the 

 first oblique division, while in Phascum, Funaria, Andreaea, and Fissidens, this 

 oblique septum is formed immediately after the first horizontal one. The apical 



Fig. 236. — Ftinaria hygronietrica; A origin of the spo- 

 rogonium ff in the ventral portion b b oi the archego- 

 nium ; (longitudinal section X500) ; B, C different further 

 stages of development of the sporogonium y and of the 

 calyptra c; h neck of the archegonium (x about 4°)- 



