APPENDIX. 
113 
peculiarly akin, as also the dilatation of the free end of the body 
into a prothallus ; on the other hand, they are differentiated by 
the’.r isolation and independent position with regard to the sorus. 
1 will conclude my remarks by pointing out that in all three 
cases of apospory now observed there appears correlated with 
the phenomenon a marked elongation of the ultimate divisions of 
the frond. Athyrium Filix-foemina, var. Clarissima, is very 
remarkable for this character ; and on the two species of 
Polystichum the lower pinnae are so characterised, while the 
upper pinnae, which nearly approach the normal form, are 
comparatively barren of prothalli. I mention this as it may form 
a clue to the discovery of the phenomenon in other Ferns which, 
like the one under special notice, may only require close 
treatment to yield similar results. 1 am therefore sanguine 
that other workers, in not only British, but exotic Ferns, may 
thus light upon new instances of the phenomenon in question, 
and so increase the opportunities of completely studying it. 
A. F. F. PLCMQStJM DltUEIlY (YOUNG FROND). 
