MUSCI AND HEPATICAE 



469 



encloses a central series, consisting of canal-cells (c.c.) which may some- 

 times be very numerous, a ventral-canal-cell (v. c.c), and the ovum (ov.). 

 At maturity the end of the neck opens in presence of water, owing to 

 pressure of mucilaginous swelling within ; a funnel-like channel then 

 leads down to the ovum (Fig. 363, vi.). Spermatozoids, motile in the 

 water, may be seen to enter it, and there is reason to believe that their 



movements are directed by dif- 

 fusion from it of some soluble 

 substance, such as cane sugar. 

 It will be noted how perfect is 

 the protection of the ovum 

 within the archegonium, and 

 that the protection continues 

 after fertilisation. This reten- 

 tion of the ovum within the 

 parent plant is a general 

 feature of subaerial vegeta- 

 tion, and may be held to have 

 been a leading feature in its 

 success. 



The result of fertilisation is 

 the Sporogonium (Fig. 355, p. 

 461). It usually appears as 

 a radially constructed body, 

 seated in the tissue of the 

 Moss Plant, and bearing at the 

 end of a long stalk (seta) a more 

 or less oval head (the capsule), 

 which at ripeness- contains very 

 numerous spores. It is covered 

 at first by a hood or cap 

 (calyptra), which falls off at 

 maturity, disclosing a lid, or 

 operculum. This finally separates by a transverse split, and falling 

 away opens the capsule, just as the lid might be taken off a covered 

 jar. In most Mosses a fringe of ragged filaments, the peristome, is 

 thus disclosed, which by their hygroscopic movements serve to 

 distribute the dry and dusty spores (Figs. 364, 367). The sporogonium^ 

 is usually green while young, but yellowish or brown when r M .e. 

 This is due to photo-synthetic tissue, which is specially developed 

 at the enlarged base of the capsule (apophysis), where also stomata 



Fig. 364. 

 Median section of an immature sporogonium 

 of Funaria. s=seta. ap.= apophysis. u' = water- 

 storage-tissue. s*. = stomata. sp.s. =spore-sac. 

 arch. = archesporium. col = columella. p = peristome. 

 op = operculum. Based on a drawing by Haber- 

 landt. ( x 20.) 



