4 PREFACE. 
scientific work, a few copies are offered for sale at about 
the cost of publication ($1.00 each, for the reports already 
issued, including the present, and 50 cts. for the revision 
of Epilobium reprinted from the second report) at the gate 
of the Garden, and by Dr. A. E. Foote, of Philadelphia, 
W. Wesley & Son, of London, and R. Friedlander & Sohn, 
of Berlin. Applications for the purchase or exchange of 
either reports or separate papers may be made also to the 
Director of the Garden. 
WILLIAM TRELEASE. 
Sr. Louis, Jan. 14, 1892. 
