252 FOUNDATIONS OF BOTANY 
In conceptacles of the other kind examine the numerous small 
sac-shaped cells (antheridia). At maturity the contents of each 
divide to form numerous very minute motile antherozoids, each with 
two delicate hairs or cilia. Dissect, by picking and by friction under 
cover-glass, a bunch of 
antheridia and note 
the branching fila- 
ments upon which 
they are borne. 
Make drawings to 
illustrate the various 
points of structure. 
295. Number of 
Antherozoids required 
for Fertilization. —The 
bulk of an odsphere 
has been estimated 
equal to that of thirty 
thousand to sixty 
thousand antherozoids, 
but apparently an 
odsphere may be fer- 
tilized by only one 
ee f BOR antherozoid. Yet a 
Ser SO large number swarm 
around each odsphere 
after both have 
escaped from the con- 
fe 
Fic. 186.— Transverse Section of Conceptacle of a 
Rockweed (Fucus platycarpus). (x about 35 ) 
came ceptacles, and often 
their movements are 
so active as to cause the rotation of the odsphere. The process of 
fertilization may be discerned in fresh material by squeezing 
odspheres and antherozoids from their respective conceptacles into 
a drop of water on a slide. In some species, as Fucus platycarpus 
(Fig. 186), antheridia and oégonia are found in the same 
conceptacle. 
h, hairs ; a, antheridia; 0, odgonia. 
