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 of 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. 75 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 



