BRYOPHYTES 85 
Vegetative structure——Note the form of the body and 
its position with reference to its support. Where is the 
youngest part of the plant? In what direction does growth 
take place? How does the plant branch? Are rhizoids 
equally distributed over all parts of lower surface? Make 
a sketch of a plant. On the dorsal (upper) surface note 
the diamond or irregularly shaped areas, in the center of 
each of which there is an opening. This opening—the so- 
called “ breathing-pore ”—leads into an air-chamber into 
which extend peculiar cells that bear chlorophyll. Sketch 
a few of the areas. Make a very thin cross-section of the 
plant and note how these chlorophyll-bearing cells are ar- 
ranged in the air-chamber. Is chlorophyll borne in all the 
cells below the air-pore? Note the partitions between the 
air-chambers. How do rhizoids arise from the lower cells? 
Draw a part of a cross-section, showing the kinds of tissues 
and their arrangement. 
Vegetative reproduction.—On the dorsal side of the 
liverwort body there are frequently cup-like outgrowths 
—cupules—in which are small bud-like bodies—the gemme 
—which, when set free, may grow directly into new plants. 
Note some of the cupules, remove the gemme, and study 
their structure. Draw. 
Sexual reproduction.—From the midrib of the liverwort 
thallus there arises a branch with expanded top bearing 
sex organs. A thallus produces only one branch, a male or 
a female. The archegonial héads have finger-like branches 
and resemble a starfish, while the antheridial heads are disks 
with lobed margin. Make a general sketch of each branch 
upon its thallus. 
By means of sections or dissections study the archegonia 
and antheridia. Note how archegonia are suspended from 
the head and how the antheridia are embedded within it. 
Younger heads will show the best archegonia. Draw, show- 
ing the structure of each sex organ. 
