286 
PHARMACEUTICAL BOTANY 
or dioecious , in which case the antheridia and archegonia arise on 
different plants. 
Order i.—Sphagnales, or Bog Mosses, including the simple genus, 
Sphagnum. Pale mosses of swampy habit whose upper extremities 
repeat their growth periodically while their lower portions die away 
gradually and form peat, hence their frequent name of Peat Mosses. 
A number of species of Sphagnum have been recently employed 
in surgery as absorbents in place of gauze. For this purpose they 
must be thoroughly cleaned and sterilized. 
Order 2.— Andreaeales, including the single genus Andreaea, of 
xerophytic habit, occurring on siliceous rock. 
Order 3.— Bryales, or true mosses, comprising' the most highly 
evolved type of bryophytes. Examples: Polytrichum , - Funaria , 
Hypnum , and Mnium. 
Life History of Polytrichum Commune (A Typical True Moss).— 
Polytrichum commune is quite common in woods, forming a 
carpet-like covering on the ground beneath tall tree canopies. It is 
dioecious, the plants being oi two kinds, male and female. 
Beginning with a spore which has fallen to the damp soil, we note 
its beginning of growth (germination) as a green filamentous body 
called a protonema. This protonema soon becomes branched, giving 
rise to hair-like outgrowths from its lower portion called rhizoids 
and lateral buds above these which grow into leafy stems commonly 
known as “moss plants.” At the tips of some of these leafy stems 
antheridia (male sexual organs) are formed while on others arche¬ 
gonia (female sexual organs), are formed. These organs are sur¬ 
rounded at the tips by delicate hairy processes called paraphyses 
as well as leaves for protection. The antheridia bear the anthero- 
zoids, the archegonia, the eggs or ova, as in the liverworts. When 
an abundance of moisture is present, the antherozoids are liberated 
from the antheridia, swim through the water to an archegonium 
and descend the neck canal, one fertilizing the egg by uniting with 
it. This completes the sexual or gametophyte generation. The 
fertilized egg now undergoes division until an elongated stalk 
bearing upon its summit a capsule is finally produced, this being 
known as the sporogonium. The base of the stalk remains imbedded 
in the basal portion of the archegonium, at the tip of the leafy 
