o2 
an inch or more in length will he found radiating from the original 
speck. 
The mode of growth in the algse consists in the division and 
sub-division of the parent cell. When a fragment is placed in a 
growing slide, and examined from time to time with a microscope, 
the colouring matter in the cell will be found gradually to separate, 
and a septum is formed. We have now two perfect cells : this 
process is repeated with startling rapidity. If the cell belongs 
to a filamentous species, it divides transversely only ; if it belongs 
to one of the frondlike species, it divides laterally as well as ti’ans- 
versely — this is well shewn in the elegant Phyllactidium pulchellum. 
The algae, as I before observed, possess neither leaves, flowers, 
nor seeds ; the method of their reproduction is one of the marvels 
that the microscope has revealed to us. If we examine a few fila- 
ments of Zygnema, (a very common conferva,) we shall probably 
detect two filaments, connected by button-like projections, on the 
edge of the cell, and we may also see that an alteration has taken 
place in the colouring matter of the two opposing cells ; it has 
assumed a globular form, and passes through the aforesaid projec- 
tions — the two masses meet and intermingle, and form the sporan 
gium ] shortly a movement will be seen, and a number of minute 
oval bodies, with two or more tails, make their appearance ; these 
are zoospores, and it is truly wonderful to observe their animal like 
movements, sometimes apparently fixed by the tails, and swaying 
to and fro like miniature balloons, preparatory to an ascent — now 
perfectly motionless — now gyrating like a top — now starting off 
with the rapidity of an express train. After the lapse of a short 
period the spore becomes languid, and motion ceases, and death 
has apparently claimed it for its own, but if we watch it attentively, 
we shall find that it is about to enter a new phase of existence ; 
motive power, indeed, no longer exists, but vitality is still there, 
and active — it gradually lengthens and expands, the cell is formed, 
and presently division takes place, and what before appeared to be 
an animal, has become a true plant. 
The green colour of stagnant water is generally occasioned by 
the presence, in countless myriads, of zoospores. Reproduction by 
means of zoospores is not peculiar to the algje ; it has been found 
that hverworts, ferns, and other forms belonging to the class crypto- 
garaia, are produced from them. It may be useful, as shewing 
