PREFACE. 



It has always seemed desirable to me to give some in- 

 struction iilong ecological lines in a general course in botany. 

 Ecology considers the external relations of plants, and no 

 field oflEers greater opportunities to awaken an interest in 

 botany than the relations existing between flowers and in- 

 sects and other agents in bringing about pollination. 



Much of the material contained in the following pages 

 has appeared before in some lectures delivered at the meet- 

 ings of the horticultural societies of this state. 1 have how- 

 ever added considerable new material. 1 have made free 

 use of published papers on the subject, especially those of 

 Robertson, Mueller, Ludwig, Trelease, Gray, Riley, Bailey, 

 Kerner and others, full credit has been given in the proper 

 places. I am also under obligations to Mr. C. R. Ball who 

 has assisted me in various ways as well as Mr. Combs; 

 Mr. E. D. Ball who made some of the insects determinations 

 for me, and some help from Prof. H. Osborn and Mr. W. 

 Newell. To all I wish to express my sincere thanks. 



