22 
D. H. Scott. 
The agreement between the stages met with in the fossil and 
those of recent germinating Fern-spores is manifest. Fig. 61 A is a 
typical early stage, 1 where only the rhizoid has developed. In B we 
have a normal young prothallus (a little younger than that shown 
in Kny’s Fig. 4, l.c.) There may very probably have been a 
rhizoid here also, which the section has missed. In C the type of 
germination appears to have been that described by Campbell in 
Osmundn Claytoniana, where the exospore is pushed up with the 
growing prothallus ; 2 a fragment, however seems to have been left 
behind, next the rhizoid. The spore D may represent Campbell’s 
other type, where the exospore remains at the base of the 
prothallus, though we cannot be certain of this, as the attachment 
■of the rhizoid is not shown. 
The germination of spores within the sporangium is not 
uncommon in recent Ferns, when, from any cause, effectual 
dehiscence has been hindered. A good case (from Pteris serrulata) 
is figured by Atkinson. 3 That this had happened in the case of our 
fossil is a fortunate accident, for otherwise it is very unlikely that 
such delicate structures should have been preserved uninjured, or 
that they could have been recognized. The spores lying loose in 
the surrounding debris do not show any clear case of germination, 
perhaps owing to damage when no longer protected by the 
sporangial wall. 
The observation of these germinating spores is of interest as 
showing that some at least of the Carboniferous Ferns followed the 
same course of development as their recent allies. The agreement 
with corresponding stages in the development of Fern-prothalli at 
the present day, leaves little doubt that in this Carboniferous Fern 
also the spores produced the sexual generation in the way familiar 
to us. It may be hoped that this form of sporangium may even¬ 
tually be referred to the Fern on which it was borne. At present we 
have no satisfactory clue to its attribution ; in the same preparation 
with the specimen described, a very beautifully preserved portion of 
1 cf. Kny, Bot. Waudtafeln. Abth. IX., 1895. Taf. XCVI. Fig. 2 
(Aspidium Filix-mas). 
J Campbell, On the Prothallium and Embryo of Osmunda Clav- 
toniana, etc., Ann. of Bot., Vol. VI., 1892. p. 52, PI. III., Fig. 6. 
3 Biology of Ferns, 1894, Fig. 12. Mr. Boodle reminds me that 
he observed spores germinating in sporangia of Todea 
hvmenophylloides. “which were ruptured but still arranged 
in sori on the lower side of the leaf.” Anat. of Hymeno- 
pliyllaceae. Ann. of Bot.. Vol. XIV., p. 484. 1900. The 
possible affinity of our fossil with Osmundacese gives this 
case a special interest. 
