102 ABOUT A FERN. [CHAP. 
in which, coiled up in a spiral, are little bodies 
thick at one end and tapering off to the other, where 
a number of cilia are developed. These bodies are 
the antherozotds (2.) 
The archegonia (¢) are cylindrical in shape, with an 
opening at the top; this opening extends as a central 
cavity to the base of the cylinder, which is occupied 
by a large cell, called the embryo-cell (e,2). Into this 
cell the antherozoids, when set free, are propelled 
by their cilia, the protoplasm mingles with that of 
the embryo-cell, and the fertilisation of the fern is 
effected. As the result of the fertilisation the embryo- 
cell divides into four cells, two above and two below. 
The two lower ones again divide and subdivide until 
it assumes a plug-shape and enters into the substance 
of the prothallus. The two upper cells give rise, one 
to the stem, or rizzome, of the new fern, and the other 
to its first rootlet. Professor Huxley thinks it pro- 
bable “that the plug-like mass absorbs nutritive 
matter from the prothallus, and supplies the rhizome 
of the young fern, until it is able to provide for itself.” 
The rhizome now grows, and sends up delicate little 
fronds (g), and the prothallus, having no further office 
to serve, gradually shrivels up and vanishes. 
Such are the phenomena connected with the repro- 
duction of ferns, and it should be remarked that the 
fern is not directly the product of the spore. In 
ferns, as in many other plants, there is here exhibited 
what is known as the “alternation of generations.” 
The spore produces, not a fern like that it was pro- 
duced by, but an organism closely resembling the 
more lowly Liverworts—the prothallus. This pro- 
