x PREFACE 
There remains the very pleasant duty of offering 
my cordial thanks to those of my friends who have 
been good enough to assist me, especially to Prof. 
F. E. Weiss, F.R.S., and Mr. W. C. Worsdell, F.L.S. 
Both of them have given me very valuable advice 
and help, and while Prof. Weiss has kindly contributed 
an introduction, Mr. Worsdell has generously relieved 
me of most of the tedious but necessary task of making 
the Index; moreover, it was almost entirely at his 
suggestion that I decided to deal in these pages with 
the relatives of the Herb Robert. 
Dr. D. H. Scott, F.R.S., has also allowed me the 
benefit of his advice whenever I sought it and Mr. H. 
St. J. K. Donisthorpe, F.E.S., has helped me with the 
entomology. 
Again I derive great encouragement from the 
interest shown in my book by friends who are neither 
botanists nor naturalists: assistance of this nature 
is invaluable, with a charm and a virtue all its own. 
Finally, my readers will, I am sure, agree with me 
that our thanks are due likewise to the photographers 
for their excellent work. 
T. A. DYMES. 
‘‘CarTHONA,’ Wrst DRAYTON, 
MIDDLESEX, 
October, 1919. 
