LIFE HISTORY OF A FILIFORM ALGA. 
91 
selves, not to any promiscuous cell which may be near tliem, 
but to the cell which immediately joins the oogonium, and 
not by mistake the cell above, but the cell below the oogonium, 
and there remain permanently fixed. What is the attraction 
powerful enough to draw them to this spot, and no other ? 
“ Surely there are more things in heaven and in earth than 
are dreamt of in your philosophy.” 
We have followed the androspores from their parent cell 
until they attach themselves to the cell immediately beneath 
the oogonium. When they have done so the base elongates 
into a kind of stem ; the upper portion also grows and 
elongates until it assumes more or less a club-shaped form. 
The apex narrows into a mouth, covered with an operculum, 
or movable lid. Meanwhile active little spermatozoids are 
being formed in the interior, and the androspores are con¬ 
verted into little male plants (nannandres), clustered around 
the oogonium, ready at any moment for their spermatozoids 
to escape and enter the little opening in the wall of the 
oogonium to fertilise the oospore which it contains. Thus, 
then, we trace this process ; the formation of an ovum or 
unfertilised spore in its ovarian sac or oogonium, and the 
same thread producing androspores (or spores of male plants) 
which escape and then attach themselves close beneath the 
oogonium, produce their own spermatozoids, which in fulness 
of time issue at the apex, by the falling off of a deciduous 
operculum, and immediately enter the aperture of the 
adjacent oogonium and fertilise the oospore. This work 
being accomplished, the male plants have no other mission 
in this world, therefore they dry up and wither away, whilst 
the oospore, now rendered feitile, passes through a period of 
rest and in due time produces a new generation. 
From these fertilized oospores we may now follow the 
young plants until we reach the point at which our history 
commenced and the cycle is complete. 
Before completing this history, we may make a diversion 
here to explain another method of reproduction which prevails 
in this interesting genus of aquatic plants. We have hitherto 
been watching a truly sexual reproduction in which male and 
female elements perform their part, but in this other method 
there is no visible evidence of sexuality ; it is, as far as 
we can judge, a purely asexual or nonsexual reproduction, 
analogous to budding in higher plants. 
In this method for the continuance of its species, any cell 
in an ordinary vegetative filament will serve. In one of these 
cells there is a turbulence in the cell contents, which at length, 
draw closer together, and in a short time an ovate body is 
