"98 The Queensland Naturat.ist. Vol. L 
a greater range in the numbers expressing the lengtli as 
a multiple of the breadth, than is given in the recognised 
works of authority. In a paper read before a society 
some time ago,* I entered somewhat fully into the details 
of the cell-structure in Spirogyra, the method of cell-division, 
and the manner in which adjacent cells in two parallel 
and contiguous threads conjugate by the formation of a 
connecting tube through which the contents of one of the 
cells pass to the other where they unite. In Fig. 7, the 
contents of one cell may be seen in the act of passing 
through the canal of conjugation and mingling with those 
of the adjacent cell. There is also another mode of union 
in Spirogyra in virtue of which Kutzing established the 
genus Rhynchonema in which he placed the forms in which 
this takes place, but as it has since been proved that the two 
methods may both be observed in one species, and even 
in the self same pair of threads, Kutzing’s genus Rhyncho- 
nema is now incorporated with S]hrogyra. The second 
method of conjugation just referred to consists in the union 
of the contents of two adjoining cells of a single filament, 
which is effected by means of a tubular passage which forms 
at the joint on one side, giving the joint a swollen appear- 
ance on that side, and affording to the contents of ^ one of 
the cells, free access to those of the other. In Fig. 1 the 
fertile thread with two spores is an illustration of this 
method of conjugation, a method technically knoAvn as 
the lateral method, whereas that first described is called 
the scalariform method, from the resemblance to a ladder 
which the conjugated filaments exhibit. Fig. I is also 
an example of a species which exhibits both the lateral 
and the scalariform modes of conjugation. 
Just as in the case of annuals among the flowering 
plants, the last spark of the vitality of the individual plant 
is consumed in the perfection of the seed, so in Spirogyra, 
after the completion of the spore, the threads decay and 
disappear, setting free the matured spores Avhich are capable 
of retaining their vitality throughout very lengthened 
periods, when conditions are unfavourable to their ger- 
mination, as in the case of drought. Thus the spores 
prevent the extinction of the species in many localities 
where, but for them, such result must inevitably occur. 
Having thus briefly described the general charac- 
teristics of the genus, and before proceeding to an account 
of the Queensland species so far as yet knoAvn, I A\ould 
offer a few observations on the principles and methods 
followed in the identification of the species, in the hope 
that some of our younger members, possessing a microscope 
and a love of plant life, may be induced to collect and 
examine the species of Spirogyrat within their reach, in 
