PREFACE 
t the point of completing the edition of »Index Filicum- it only remains 
A to me to return my sincere thanks for the unanimous recognition, with 
which the professionals have received my work and particularly for the valuable 
assistance that has been rendered me from different sides. 
The book, as a whole, is my. own work; only in a few instances have I 
found it necessary to seek advice and help. In the first place I must here 
mention the name of the famous pteridologist Dr. H. CHRIST, Basle, without 
whose assistance I should hardly have succeeded in getting the book published. 
From the very first Dr. CHRIST has embraced my work with the greatest 
interest and during the time of editing he has very often helped me in diffe- 
rent ways. For this I thank Dr. CHRIST most heartily. Next I must mention 
Mr. A. GEPP of British Museum. Mr. GEPP has with the utmost readiness 
excerped several works to which I had no access, and thereby he has contri- 
buted to my work being well nigh complete. I also take the opportunity to 
beg Mr. GEPP accept my best thanks. Further I must thank Prof. Dr. G. 
HIERONYMUS, Berlin, who has unravelled certain difficult groups of forms 
of Asplenium for me. 
In conclusion it is my pleasant duty to thank the DIRECTORS OF THE 
CARLSBERG FUND, Copenhagen, for the pecuniary support they have given 
me as an aid towards the publication, without which it would have been im- 
possible for me to bring out the book. 
I herewith surrender my work to the pteridologists and others studying 
the science of botany, and I only beg that they will forgive the no doubt nu- 
merous mistakes and errors, which it has been impossible to avoid. As it is 
my intention (time and health permitting) at some future time to issue a 
Supplement, I shall be most grateful for all communications pointing out 
omissions and errors. : 
Copenhagen, Sept. 15. 1906. 
Carl Christensen. 
