PREFACE IX 



Wise Sutton for some of the drawings. Mr. Alban Stewart pre- 

 pared the camera lucida drawings of tissues of Avicennia, Psidium 

 and Mangrove, from materials collected by him in the Galapogos 

 Islands. Mr. L. M. Peace made the photomicrographs appearing 

 here, prepared many of the sections from which the drawings 

 were made, and gave me many valuable suggestions for the 

 chapters on microtechnic. 



My thanks are due my colleagues, Dr. M. A. Barber, Dr. C. E. 

 McClung, Dr. F. H. Billings, and Prof. Chas. M. Sterling for 

 reading and critizing different parts of the book, and to Ada 

 Pugh Stevens for reading all of the proof sheets. 



W. C. Stevens. 



University of Kansas. 



