PREFA CE. Vll 



Illustrations. — The large majority of the illustrations are new, 

 and were made with especial reference to the method of treatment 

 followed in the text. Most of the photographs were made by 

 the author. Others were contributed by Professor P. H. Mell, 

 of the Alabama Polytechnic Institute, Auburn, Ala.; Professor 

 Rowlee, Cornell University ; Mr. H. J. Webber, Washington, 

 D. C. ; by the New Jersey Geological Survey through the courtesy 

 of Mr. Gifford Pinchot, of New York ; by Mr. B. M. Duggar, 

 Cornell University, and Mr. Herman von Schrenk, of the Mis- 

 souri Botanical Garden. 



Many of the drawings, especially those of microscopic objects, 

 were made by the author ; others by Mr. H. Hasselbring, Cor- 

 nell University, and Dr. Bertha Stoneman, now professor of 

 botany in the Huguenot College, Wellington, Cape Colony, 

 South Africa. The drawings to illustrate the gross characters of 

 plants were made by Mr. AV. G. Holdsworth, Michigan Agri- 

 cultural College ; Mr. Joseph Bridgham, Providence, R. I. ; 

 Messrs. W. C. Furlong and W. C. Baker, Cornell University ; 

 and a few by Miss Edna Porter, Buffalo, N. Y., and by Mrs. E. L. 

 Nichols and Mrs. J. G. Needham, Cornell University. Pro- 

 fessor Chas. A. Davis kindly furnished the sketches from which 

 the drawings of the transformed trillium flower were made. 



Other illustrations have been obtained from the following 

 sources : from the author's Study of the Biology of Ferns, 

 through the courtesy of the Macmillan Co.; and from the 

 Annals of Botany, Jahrbucher fiir wissenschaftliche Botanik, 

 Flora, Botanical Gazette, Vines' Student's Text Book of Botany, 

 and Warming's Botany. 



Above all the author is under great obligations to Professors 

 Ikeno and Hirase, of the Imperial University of Japan, Tokio, 

 for their unparalleled courtesy in sending drawings of the sperma- 

 tozoids, and of fertilization, in cycas and gingko, in advance of 

 their publication. 



Cornell University, June, 1898. 



