FRESH-WATER ALGH. 251 
over the earth in a very thin intricate fleece of a 
bright grassy-green colour. The filaments are 
tubes containing an internal green pulverulent 
mass like the other conferve ; but the fructifica- 
tion is developed on the outside in the form of 
dark green homogeneous vesicles attached to 
the filaments. The Vaucherias are plants of 
higher organization than most of the other con- 
fervz, and are distinguished by the comparatively 
enormous cells of which they are composed. 
They may be known from all other conferve 
with which they may be associated by the fact 
of their branching without joints. They are 
indeed composed of only one cell, sometimes 
attaining many inches-in length. They are re- 
produced by very large oval gonidia, which are 
covered with innumerable cilia, and in con- 
sequence endowed with active motion, while 
they are vivified by the agency of spermatozoa. 
This mode of reproduction by motile spermatozoa, 
strange to say, connects the lowest class of plants 
with the highest members of the animal kingdom 
in the exercise of their most important function. 
The various species of conferve are known in 
country places by the popular name of crow-silks, 
and are used when dried for stuffing beds, for 
making wadding for garments, and some of them 
even for manufacturing paper. Pliny mentions 
