ALG 63 
No special non-sexual reproductive organs occur in 
these plants, beyond the separation of small fragments, 
usually nodes, which may, under proper conditions, de- 
velop into new individuals. 
The sexual organs, antheridia and odgonia, are ex- 
tremely complicated, especially the former, and differ 
very much from those of all other alge. They show 
certain analogies with the reproductive organs of some 
of the lower mosses, this being especially the case with 
regard to the spermatozoids, which are strikingly similar 
to those of some mosses. A single large spore results from. 
the fertilization of the egg-cell, which is surrounded by a 
protective covering formed by a series of cells about it. 
The spore on germination produces a simple conferva- 
like filament, or “ protonema,” upon which the fully de- 
veloped plant arises as a lateral branch. As this is 
somewhat like the formation of the leafy stems in the 
common mosses, it has been suggested that there may 
be some genetic connection between the latter and the 
Characee ; but this is highly improbable in view of the 
great differences in the structure of the plants of the two 
groups, although the analogies in the structure of the re- 
productive organs may indicate a remote relationship be- 
tween them. 
THE Brown AND RED ALG& 
While the green alge are for the most part inhabi- 
tants of fresh water, the two other great groups of 
Alge are mostly found only in the sea, where they con- 
stitute the most conspicuous features of the marine 
flora. Both classes include plants of much greater size 
and complexity than any green alge, some of the great 
