TO 



ROBERT GRAHAM, M.D., F.R.S. Edin., F.L.S. 



4c. 4c. %c. 



AND 



REGIUS PROFESSOR OF BOTANY IN THE UNIVERSITY OF EDINBURGH. 



3Iy deab Sir, 



Fellow.labourers as we are in the 

 same field, occupied professionally in the same pursuit in Sister 

 Universities of this country, and alike anxious for the advancement 

 of our favourite science ; — these may he considered, in themselves, 

 sufficient reasons why I should wish to dedicate the following pages 

 to you. But I have a still stronger inducement ; namely, that I 

 may thereby record the friendship which has, I believe, almost from 

 the first of our acquaintance, subsisted between us, and which I 

 fervently hope may continue during the remainder of our lives. 



That this work may be found useful to your students, as well as to 

 my own, and that your zealous endeavours to promote tJie interests 

 of your Class, and of Botany in general, may be rewarded by the 

 most happy success, are amongst the sincerest wishes of, 



Bear Si?', 



Your faithful and affectionate Friend, 



THE AUTHOR. 



