82 EVOLUTION OE LIRE 
of distinct germinal masses, which. unite whilst free in the 
water, to form a spore, a process corresponding to the 
so-called conjugation of the Spirogyra. 
PEORID AL: 
The red or rose-colored Algz, though much smaller 
than the Fucoide, surpass them greatly in beauty of color- 
ing and delicacy of form. They are commonly known as 
red sea-weed, and, when dried and arranged on paper, they 
are often offered for sale. The Florid& (Fig. 101), or Red 
Alga, are from six inches to two feet high, offering in their 
coloring different shades of red, rose-red, and purple. Their 
form varies from that of a filament or stalk to that of a 
leaf or feather. To see them in perfection, they must be 
studied in a tropical climate. The reproduction of the 
Floride is still involved in some mystery. There are in 
many species tetraspores (Fig. 102), which are formed by 
the division of the so-called perispore into four spores, 
which appear to correspond with the zoospores of the 
lower Algee. Besides these tetraspores, other reproductive 
bodies arise in some species from the union of two germs, 
which may be looked upon as the representatives of dis- 
tinct sexes. While the Green, Brown, and Red Alge 
differ greatly in their size, form, coloring, and reproduction, 
they all agree in their cellular structure. When we com- 
pare a single individual of the Chlorococcus—so minute 
that hundreds of thousands might rest on the head of a 
knitting-needle—with the gigantic Macrocystis, notwith- 
standing minor differences, we find the essentially cellular 
structure of both to be the same. The group of Alg is, 
therefore, a natural one, the extremes being connected by 
innumerable links, offering a gradual transition from micro- 
scopic forms to the largest of plants. In the preceding 
chapter we have given reasons for supposing it probable 
| 
| 
