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 antherozoids (i.) 



The archegonia (e) 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 rhizome, 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- 



