Fig. 147.
Portion of thread of œdogonium
showing antheridia.
Fig. 148.
Portion of thread of œdogonium
showing upper half of egg open,
and a spermatozoid ready
to enter. (After Klebahn).
317. Sexual reproduction. Antheridia.—The antheridia are short cells which are formed by one of the ordinary cells dividing into a number of disk-shaped ones as shown in [fig. 147]. The protoplasm in each antheridium forms two spermatozoids (sometimes only one) which are of the same form as the zoogonidia but smaller, and yellowish instead of green. In some species a motile body intermediate in size and color between the spermatozoids and zoogonidia is first formed, which after swimming around comes to rest on the oogonium, or near it, and develops what is called a “dwarf male plant” from which the real spermatozoid is produced.
Fig. 149.
Male nucleus
just entering
egg at left side.
Fig. 150.
Male nucleus
fusing with
female nucleus.
Fig. 151.
The two nuclei
fused, and
fertilization
complete.