MUSCI AND HEPATICAE 



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is a club-shaped body, seated on a short massive stalk, and it is 

 frequently large enough to be seen by the naked eye. It consists of a 

 peripheral wall of tabular cells, covering a mass of cubical spermato- 

 cytes (vi.). It bursts when ripe at the distal end (viii.). There is often a 

 special cap of mucilaginous cells which produce and control the pore 

 of exit. The spermatozoids can then escape in a thin stream, 

 embedded in mucilage from which they soon escape. In cases where 



Fig. 304. 

 i.-^'. Stages in de^'elopnient of the aixliegoniuin of Fnnariii, after Campbell ( x 400). 

 ^"i. Mature arcbegonium of Atidreaca, after Kiihn (:-. 250). i. sliows co\'er-cell 

 separated from central-cell (shaded.) ii. iii. co\'er-cell (.r) undergoing segmentation 

 as an initial cell, gi\"ing rise to three rows of lateral and one of basal segments : the 

 former constitute the " neck." the latter are the canal cells, iv. shows the ovum [ov], 

 ventral canal cell {i'.f.c), and canal-cells {c-c). V- shows the apex of the neck before 

 rupture, with canal-cells fee.) within. 



the perichaetial leaves face upwards, a shower of rain would bring 

 the rupture about, and the mucilaginous contents may be seen and 

 collected on a slide in a drop of water. The biciliate spermatozoids 

 may then be observed in active movement (Fig. 303. vii.). 



The archegoniinn is a flask-shaped body with a long neck (Fig. 304). 

 It is seated on a massive stalk, and it also arises from a single superficial 

 cell. When mature it consists of a peripheral wall, which in the lower 

 ventral portion is double, but the neck consists of a single layer built 

 up of six rows of cells, as against four in the Pteridophyta. Tlie wall 



