SOME TYPES OF FLOWERLESS PLANTS. 239 
295. 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 sufficient here to give an outline of the 
process. The protonema develops buds, one of which is shown in Fig. 
206, and the bud grows into an ordinary moss plant. This plant, in the 
case of the pigeon-wheat moss, bears organs of a somewhat flower-like 
nature, Fig. 205, which contain either antheridia, Fig. 204, organs 
which produce fertilizing cells called antherozoids, or archegonia, Fig. 
205, organs which produce odspheres (§ 275), 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 odsphere, by the penetration of anthero- 
zoids to the bottom of the flask-shaped archegonium, the development 
of the odsphere into an urn begins, the latter rises on its slender stalk, 
while the upper part of the archegonium is carried with it and persists 
for a time as the hood, Fig. 202, c. 
MOSSES. 
296. Mosses have Specialized Organs.—In his examina- 
tion of a moss the student at once recognizes it as a distinct 
advance from the kind of plant hfe exemplified by any of the 
eryptogamous types which he has previously studied. Root, 
stem, and leaf, as found in flowering plants, are represented 
by organs of similar function, though not of similar structure 
to true roots, stems, and leaves. The principle of physiological 
division of labor, so characteristic of the higher plants, is 
fairly exemplified in mosses. Although destitute of true 
flowers, they possess flower-like organs which may be either 
moncecious or dicecious. — 
297. Alternation of Generations. — In mosses, as in the 
simpler liverworts, below them, and the more complex ferns, 
above them, the reproductive process includes what is known 
as an alternation of generations. That is to say, the organs 
of reproduction produce a spore which does not grow directly 
into a new individual like the parent. The fertilized odsphere 
