242 ELEMENTS OF BOTANY 
spores, if sown on moist earth, will each develop into a slender, 
branched organism, consisting, like pond-scum, of single rows of 
cells (Fig. 168) called the protonema. 
310. Other Reproductive Apparatus. — The student cannot, with- 
out spending a good deal of time and making himself expert in the 
examination of mosses, trace out for himself the whole story of the 
reproduction of any moss. It is sutficient here to give an outline of 
the process. The protonema develops buds, one of which is shown 
in Fig. 168, and the bud grows into an ordinary moss-plant. This 
plant, in the case of the pigeon-wheat moss, bears organs of a some- 
what flower-like nature, which contain either antheridia (Fig. 169), 
organs which produce fertilizing cells called antherozoids, or arche- 
gonia (Fig. 170), organs which produce egg-cells, but in this moss 
antheridia and archegonia are not produced in the same ‘“moss- 
flower.” The plants therefore correspond to dicecious ones among 
flowering plants. 
After the fertilization of the egg-cell by the penetration of 
antherozoids to the bottom of the flask-shaped archegonium, the 
development of the egg-cell into a sporophite begins; the latter rises 
as a slender stalk, while the upper part of the archegonium is 
carried with it and persists for a time as the hood or calyptra. 
