1877.) Reproduction in Fresh- Water Algee. 523 
cells, and in them the spermatozoids (Çe, c, e). The odgonium be- 
comes at first more completely filled with contents than the re- 
maining cells; immediately before fertilization the protoplasm 
contracts and forms, as in Vaucheria, the odspore, in the interior 
of which the grains of chlorophyll are densely crowded. Im- 
mediately after fertilization the odspore surrounds itself- with 
a membrane which afterwards, like its contents, assumes a brown 
color. The odspore remains inclosed in the membrane of the 
oégonium, which separates from the neighboring cells of the fila- 
ment and falls to the ground, where the odspore passes its period 
of rest. When it awakes to new activity the odspore does not it- 
self grow into a new’plant, but its contents divide into four swarm- 
spores, which escape together with the inner skin of the odspore, 
and, after this latter is dissolved, swim away. After becoming 
stationary each grows into a new plant.” 
(Fic. 94.) BATRACHOSPERMUM. 
The last example, under this head, which space will admit of 
giving is one of a very few members of the family of red sea- 
weeds, which condescends to live in fresh water, namely, Batra- 
chospermum, or, as it is commonly called, frog-spittle. It 
tows in tufts upon the rocks and pebbles in the bottom of run- 
nmg streams, a small portion of which is shown in Figure 94, a, as 
it appears to the naked eye. ‘The plant is made up of a central 
axis with a large number of branches radiating from it at quite 
regular intervals, giving a necklace-like appearance to the fila- 
ments, The male element is in the shape of small cells borne sin- 
gly on the tips of the branches (b, b). The female part is a large, 
Peculiar-shaped cell situated on a main branch down near the 
central cylinder (¢). The antherozoids have no cilia, and fall from 
their attachments and are carried about by the water. When 
