MORPHOLOGY 
Nemalion. This marine form will serve to illustrate the simpler 
red algae. It is a branching filament, and probably produces no tetra- 
spores. 
Antheridia. The antheridia occur in clusters at the ends of short 
branches (fig. 146), each antheridium being a single cell, which at first 
contains a single nucleus. This nucleus divides, so that the protoplast 
of the mature antheridium contains two male nuclei. Physiologically, 
therefore, the an- 
theridium contains 
two sperms, but 
they are not organ- 
ized as morpho- 
logically distinct 
sperms. This bi- 
nucleate protoplast 
is discharged from 
the antheridium, 
and not being cili- 
ate it is carried by 
water currents to 
the female organ. 
This non-motile 
sperm, or sperm 
complex, is usually 
called a sperma- 
tium, but there is 
FIGS. 146-148. Nemalion: 146, branch showing antheridia no special ad van- 
forming at the tips; 147, the procarp, consisting of trichogyne ^ Q m multiplying 
and carpogonium (in the latter the male and female nuclei are 
observed, the former having passed in from the trichogyne); * ne names 
also showing two other cells with the broad cytoplasmic con- male Cell. The 
nections; 148, a'cystocarp, showing the carpospores being cut special name Was 
off at the tips of short branches, which have arisen from the , 
fertilized carpogonium. felt to be necessary 
when motile sperms 
were called spermatozoids or antherozoids, but the general term sperm 
can be applied to non-motile as well as to motile male cells. 
Female sex organ. The female sex organ of Nemalion illustrates, 
perhaps in its simplest form, this remarkable structure among the red 
algae, which usually consists of several cells and is called the procarp. 
In Nemalion the procarp consists of what may be regarded as two cells 
146 
