372 Farmer and Hill. — Arrangement and Structure 
our knowledge, and many discrepancies in the statements 
made respecting even important details. Furthermore, there 
is not a single species concerning which we possess anything 
approaching a complete account of its structure at different 
periods of its development. This latter circumstance is 
largely due to the difficulty of obtaining suitable material ; 
and it is because we have been fortunate in possessing a fairly 
complete series of young plants of Angiopteris evecta , Hoffm., 
supplemented by specimens of Marattia fraxinea , Smith, 
and Kaidfussia aesculifolia , Blume, that we venture to en- 
deavour to fill in some of the gaps in our knowledge of these 
plants. 
It is not to be expected that we shall be altogether 
successful in this attempt. Apart from the fact that there 
necessarily exists a certain degree of variety in the structure, 
even of individuals of the same species, there is always the 
difficulty of correctly appreciating the relative importance of 
anatomical details in connexions other than with those which 
happen to fall more or less immediately within the purview 
of the investigator at the moment. Details which in one 
decade appear to be trivial, may in the next assume an 
unexpected significance, and it is perhaps hardly possible 
for any anatomical treatise to be otherwise than tinged with 
the local colour of contemporary thought. 
We desire at the outset to express our indebtedness to the 
Regius Keeper of the Royal Botanic Garden, Edinburgh, to 
the Director of the Botanic Gardens at Peradeniya, to Profs. 
F. W. Oliver and A. G. Tansley, and to Mr. H. Wright, for 
their kindness in supplying us with material that has proved 
of such value in supplementing our own stock. 
Passing over the older references to the group, the first 
writers who seem to have endeavoured to deal seriously with 
the anatomy of the group were De Vriese and Harting in 
1853 1 . 1 ° this Memoir the task of working out the anato- 
mical characters appears to have been undertaken by the 
latter of the two collaborators. The results were very incom- 
1 Monographic des Marattiacees, par W. H. de Vriese et P. Harting, 1853. 
