FERNS. 227 



which they are rapidly propelled through the water. The 

 cellular bodies from which these are discharged are termed 

 the antheridia of the ferns, and are in their physiological 

 nature the representatives of the pollen of the flowering 

 plants. At a somewhat later period other cellular bodies 

 of larger size and more complex structure are found in 

 small numbers about the central part of the lower surface 

 of the prothallium on the thickened portion, situated 

 between the notch and the part where the radical filaments 

 arise. These, the pistillidia or archegonia of the ferns, are 

 analogous to the ovules or nascent seeds of flowering 

 plants, and contain, like them, a germinal vesicle, which 

 becomes fertilized through the agency of the spiral fila- 

 ments mentioned above, and is then gradually developed 

 into an embryo plant possessing a terminal bud. This 

 bud begins at once to unfold and push out leaves with a 

 circinnate vernation, which are of a very simple form at 

 first, and rise up to view beneath the prothallium, coming 

 out at the notch : single fibrous roots are at the same 

 time sent down into the earth, the delicate expanded pro- 

 thallium withers away, and the foundation of the perfect 

 fern plant is laid. As the bud unfolds new leaves, the 

 root-stock gradually acquires size and strength, and the 

 leaves become larger and more developed ; but it is a long 

 time before they assume the complete form characteristic 

 of the species." 



These observations on Ferns have acquired vastly- 

 increased interest from the subsequent investigations of 

 Hofineister, Mettenius, and Suminski, on the allied Cryp- 

 togams, and, above all, from Hofmeister's observations on 

 the processes occurring in the impregnation of the Coni- 

 fers. Not only have these investigations given us a satis- 

 factory interpretation of the archegonia and antheridia of 

 the Mosses and Liverworts, but they have made known 

 and co-ordinated the existence of analogous phenomena 

 in the Equisetacece, Lycopodiacece, and Rhizocarpece, and 

 shown, moreover, that the bodies described by Mr. Brown 

 in the Conifers, under the name of " corpuscles," are 

 analogous to the archegonia of the Cryptogams ; so that a 

 link is hereby formed between these groups and the higher 

 flowering plants. 



Q 2 



