The Sporing of the Fern 253 
The first antheridia appear when the prothallus 
is three or four weeks old. They are most often 
formed toward the point of the heart, and are 
scattered over its lower surface, apparently without 
definite order. 
Each antheridium is, at first, a single cell pro- 
truding slightly from the surface of the heart, and 
looking deceptively like a young root-hair. 
Grown older, it is a little chamber, with a single 
layer of cells forming its encompassing wall, and 
with its interior packed quite full of tiny globes. 
When the antheridium has reached fullest matur- 
ity the cells, which wall in the little chamber, ab- 
sorb water freely, swell, and burst open. 
The minute globes, which have been cribbed, 
cabined, and confined, are now set free. Each 
globe is what botanists call a ‘‘mother-cell,’’ and 
coiled up inside it lies 
something which looks x % . ¥ 
like a strap, with a nar- a) 9 F 
rower and a broader end. 
rere Se 
This is an ‘‘ antherozoid ” BS 
. Fic. 69.—Antherozoids of Pteris 
(Fig. 69). Soon after eos aie 
the mother-cell comes out (From the Vegetable World.) 
of the antheridium it bursts, and the antherozoid, 
which has been lying in it, curled up and mo- 
