AUTHOR'S NOTE 
T HE galls arising in plant tissues through the 
presence of parasitic insects and fungi are of 
peculiar interest and significance, and offer a most 
attractive field of investigation, abounding in problems 
awaiting elucidation, some of them of great economic 
importance. 
It was my first intention to publish a descriptive 
catalogue only. The volume has assumed its present 
form in the desire to meet the wishes of those who 
assured me that some introductory chapters were 
needed. I have not attempted any detailed considera¬ 
tion of the morphology, etiology, and biology of galls; 
such may be found in Dr. Kuster’s recent book, “ Die 
Gallen der Pflanzen.” 
I wish to offer my sincerest thanks to many friends 
whose names appear in the following pages—in par¬ 
ticular, to Sir Jonathan Hutchinson, who has kindly 
contributed the preface and loaned several blocks; to 
the Rev. E. N. Bloomfield for much help, especially in 
the preparation of the notes on dipterous galls, and to 
Miss Mary K. Spittal for the great trouble she has taken 
in the preparation of the most excellent coloured plates. 
It is worthy of note that this is the first book to give 
coloured illustrations of galls other than those occur¬ 
ring on the Oak. I hope that readers will assist towards 
XI 
