FERNS, APOSPOROUS AND APOGAMOUS. 



THE normal life cycle of ferns, owing to the micro- 

 scopic character of their reproductive apparatus, 

 long baffled the comprehension of botanists. But some 

 half a century ago, starting with the observations of Naegeli 

 and Suminski and culminating in those of Hofmeister, 

 the whole course of their ontogeny has been cleared up. 

 The fern plant, as ordinarily so-called, produces on the 

 back of its leaves or fronds, countless numbers of spores, 

 which are formed within minute capsules or sporangia. 

 When these spores germinate they give rise, not to a new 

 fern plant, but to a leaf-like scale — the Prothallus. Upon 

 the lower surface of this the sexual organs arise, and within 

 them the sexual cells themselves are differentiated, and as the 

 result of the fertilisation of one of the female cells or 

 oospheres, by the male cell or antherozoid, a new fern plant 

 arises. Thus in normal cases a regular alternation of a 

 sexual with a sexless generation is seen. But although 

 this is the course followed by the vast majority of the ferns 

 which have been hitherto investigated, it is not the only 

 one open to the plants. Thus Prof. Farlow in 1874 dis- 

 covered that the formation of the sporophore (fern plant) 

 generation might arise directly from the oophore (prothallus) 

 generation, without the intervention of sexual organs, by a 

 process resembling ordinary budding. De Bary, who 

 followed the matter further, found that several ferns other 

 than that examined by Farlow reproduced themselves in 

 the same fashion, to which phenomenon the name of 

 Apogamy was given, the marriage link being eliminated. 

 Curiously enough De Bary found that a variety of one of 

 our most vigorous British ferns reproduced itself constantly 

 in this asexual manner, though the common form exhibited 

 no abnormality in this respect. Recently, however, L. 

 Kny, 1 pursuing these investigations further, has found the 



1 Entivickehing von Aspidium Filix mas. Sk'., i Theil., L. Kny, 

 Berlin. 



