THE FERNS 147 



again there was no special mechanism of the kind 

 at all. 



The spores, so far as has been observed, were all 

 of one kind, and correspond in dimensions to 

 those of recent Ferns. 



The same question might arise here as in the 

 case of other Palaeozoic plants resembling Ferns 

 were they true Ferns or not? It so happens 

 that we have evidence of an unusual kind bearing 

 on the point. In more than one case the spores 

 still enclosed in the sporangia of Primofilices 

 have been caught in the act of germination, and 

 are so well preserved that the details of the 

 process are clear (see fig. 15). The stages ob- 

 served agree quite well with corresponding early 

 stages in the development of recent Fern-prothalli. 

 It is well known that in modern Ferns (including 

 members of the Osmundaceae) germination not 

 uncommonly takes place inside the sporangium, 

 if, owing to damp weather or other causes, the 

 spores have failed to be discharged. The cases 

 observed in the fossils may have been equally 

 accidental; if so, it was a fortunate accident for 

 botanists; the evidence of the germinating spores, 

 in connection with all the other characters of the 

 plants, can leave no reasonable doubt that the 

 Primofilices were really an early race of true Ferns. 

 As we have seen, they show direct continuity with 

 the family Osmundaceae; they also have points 



