THE AUSTRALIAN NATURALIST. 165 
Lhe leaves (Wigs. 2 and 3) are crowded and imbricate (Fig. 
1), and are sheathed at the base; they taper towards the 
apex; the margin is serrated. If a cross section (Fig. 2) of a 
leaf be cut, there can be seen (a) vertical rows of cells called 
lamellae; (b) below these is the blade or lamina. The 
apical cell of each lamella is enlarged and colourless, while 
the others contain chloroplasts. These lamellac are the 
chief organs of photosynthesis (manufacture of foods). The 
cells of the lamina or blade ure chiefly conductive in function, 
though a few chloroplasts occur in the outer cells. 
The leaves are specially adapted for xerophytie conditions. 
When dry weather prevails the leaf curls round the stem, pring- 
ing the upper colourless cells of the lamellae together, so that 
a curtain is formed to prevent too rapid transpiration. On 
applying water to the dry stems, the leaves uneurl and the plant 
freshens up within 20 minutes. 
The aerial stem is continued below the.ground to form a 
rhizome, which is covered with a fur of thickly matted rhizoids. 
Dawsonia is dioecious, the imale and female “flowers” being 
on separate plants. The male flower-clusters consist of rosette- 
like structures at the apex of the stems (Fig. 4). On the edges 
are rows of short leaves: In the centre are numerous pear- 
shaped multicellular antheridiu (Fig. 5), which contain motile 
flagellate antherozoids. Between the antheridia are numerous 
paraphyses which are multicellular, and at the apex broaden out 
into several rows of cells. Chloroplasts occur.in the waus of 
the antheridia. 
The female flowers (Figs. 6 and 7) are like ordinary buds in 
outward appearance, hence are very hard to find. I had to 
dissect dozens of buds before discovering any of the arche- 
gonia. -I found only a few archegonia on each plant: the 
neck of the archegonium was extraordinarily elongate, and the 
oosphere or ege cell very small. 
.The paraphyses are long and multicellular, but differ from 
those of the male in being of one cell in thickness throughout. 
As fertilization oceurs by means of water, Dawsonia retains 
one character of its algal ancestry. The antherozoid swims 
through moisture, enters the neck of the archegonium ana 
reaches the egg cell or oosphere, and fertlisation takes place. 
The resulting cell or oospore produces the sporophyte or spore- 
producing plant. which is the asexual generation. In mosses, 
this is partly parasitic on the eametophyte or Moss Plant. 
