OF SOUTH AUSTRALIA. 
117 
The female organ is the earpogonium arising from an initial cell near 
the base of a lateral filament from the central core, but it acts as an 
apical cell and proceeds to cut off a number of daughter cells, usually three. 
The apical one becomes the earpogonium, at first rounded, but soon 
producing a long, hair-like protuberance at the distal end, the trichogyne, 
and this becomes the receptive portion of the organ while the swollen base 
contains the female nucleus and is the egg proper. Sometimes the complete 
female reproductive organ is termed a procarp, in this case consisting of 
the earpogonium plus the supporting cells, but Kylin’s definition of a 
procarp restricts the term to the earpogonium plus an auxiliary cell or 
auxiliary mother cells, and as these are not formed in Nemalion the term 
cannot be applied in its properly accepted sense here. 
A non-motile, uninucleate spermatium is passively carried by water 
currents to the receptive trichogyne upon which it lodges, and the walls 
between the two break down at the point of contact allowing the male 
protoplast to pass into the trichogyne. There it divides almost 
immediately to produce two male nuclei which pass down the trichogyne, 
and one of them fuses with the single carpogonial nucleus to form a zygote. 
The zygote nucleus increases in size, then divides meiotically into two 
daughter nuclei, one of which, the lower, disintegrates ; the other divides 
a number of times and the daughter nuclei so formed migrate to peripheral 
portions of the cell which later begins to form protuberances, from 
which short compactly-branched filaments, the gonimoblasts, arise. 
The terminal cells of these filaments become swollen to constitute a carpo- 
sporangium, the wall of which ruptures at maturity to liberate carpospores, 
and this is often followed by a proliferation of a new carposporangium 
within the wall of the old one so that several successive carposporangia may 
be proliferated in the one season. On germination the carpospore gives rise 
to a normal Nemalion plant. 
Thus we see that there is a distinct alternation of generations with a 
definite gametophyte generation represented by the normal plant, and a 
definite sporophyte generation, reduced to the gonimoblast filaments on 
which carpospores are produced. The haploid chromosome number is eight 
(i.e., of the thallus and carpospores), and of the gonimoblasts and carpo- 
gonium 16, the diploid number. Diagrammatically the life- cycle can be 
represented as in Fig. 1. 
(b) Polysiphonia . — A number of species are known from the Southern 
Australian region, varying in size from small epiphytes to forms 20 cm. or 
30 cm. high. They are typically bushy, with dichotomous, alternate or 
irregular branching. The stem or branch consists of a central septate tube 
or siphon, usually small, surrounded by a row of larger cells, which are in 
many species very regularly arranged in transverse tiers. These pericentral 
cells vary from four to 24, but are usually constant for a species. In some 
of the larger species cortication may occur, and although the pericentral 
cells are still clearly visible in a transverse section, the articulate nature of 
