AUTHOR'S NOTE 



'T^HE galls arising in plant tissues through the 

 J- 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 



