ON THE MODE OF GROWTH OF SOME OF THE ALG.E. 
5 
antherozoids are formed, itself is the antheridium (like those 
before described in the seaweeds), from which they escape in due 
time. In the other process is matured an oval body (fig. 7, 6), 
which represents the ovule, or future seed of the higher orders.. 
An opening in the apex of the process leads down to it, and 
through this the antherozoids pass to fertilise it. After a time* 
this ovule escapes by the solution of the wall of the process, and 
acquires a firm external cell-wall. But unlike the other spore 
above described, it has no power of motion ; though ultimately 
it grows out, as the other spore, into an elongated tube like its 
parent. 
This plant can be observed in the early spring in a state of 
fructification, as soon as the frosts have abated ; the earlier the 
better. They can be preserved for observation on the surface of 
a pot filled with ordinary garden mould, or sand, kept well 
moistened. If placed in the sun, it will be best to invert a glass 
over it. It may be found fructifying very well on the shady 
sides of the furrows in fields. 
Thus, then, in this plant we have two forms by which multi- 
plication of the species takes place, one by throwing off a 
“zoospore,” the other by the fertilisation of a cell, which may 
be called the ovule, or 66 oospore,” or egg-spore. 
We will now direct our attention to a third form to be ob- 
served in a considerable section of the confervoids ; and in 
doing so, it will be well to watch the whole life-history of one of 
the plants in w T hich it occurs, as far as at present known. Let 
us take the common Spirogyra, of the family Zygnemacese. 
From early spring to late autumn may be found in ponds 
and pools, the sweeter and clearer the better, a number of fila- 
ments of light-green colour, of an inch or two in length. Place 
these under the microscope, and you will at once recognise the 
plant by the beautiful green spiral band above-mentioned, to 
which the plant owes its colour. 
There are many species, but they all are very similar in pro- 
ducing the phenomena to be immediately mentioned. 
It will next be noticed that it is divided into a number of 
compartments or cells, joined end to end linearly (fig. 8). In 
some species there are more than one green band, two or three,, 
like a many-threaded screw. In a few there are two spiral 
bands, which run in opposite directions. 
In the active growth of the plant, it may be observed that the 
component cells divide into two by sending a process across, or, 
as some believe, it is effected by a separation of the contents 
into two equal halves, and then each half throwing a cell-wall 
around itself. However this may be, the one cell becomes now r 
two. If this continues with rapidity, each cell is much shorter, 
but after a time the growth of each part goes on, and thus the- 
