PREFACE Xlll 
demonstrated by twenty years of trial to possess large 
teaching value. Thus, for example, we have Ascophyllum 
Sphagnum, Anthoceros, Cycas, and Erythronium in the 
text, to be supplemented by Fucus, Polytrichum, Marchan- 
tia, Zamia, and Trillium in the laboratory. By this plan 
the laboratory work can never degenerate into merely 
having the student pretend to "verify" the statements in 
the text. 
It is anticipated that a laboratory guide, planned to 
accompany this text and carry out the idea just outlined, 
may soon become available. 
In the matter of illustrations, the author has been most 
fortunate in being able to command the services of Miss 
Maud H. Purdy for the preparation of all original draw- 
ings, and of Mr. Louis Buhle, photographer at the Brook- 
lyn Botanic Garden, in making most of the photographic 
negatives and prints not otherwise acknowledged in the 
legends. For those so acknowledged the author expresses 
here his best thanks to authors and publishers who have 
freely granted permission to reproduce copyrighted as 
well as uncopyrighted illustrations. The collections of 
living plants, photographs, and drawings at the Brooklyn 
Botanic Garden have been freely at the disposal of the 
author, and grateful recognition is here made to that insti- 
tution for the exceptional opportunities which it has 
afforded. 
Special appreciation is here recorded for permission from 
Prof. David M. Mottier and Prof. Harlan H. York to 
reproduce, in advance of their own publication, Figs. 8 
and 263, respectively. 
Specifically, acknowledgment is made to authors and 
publishers, for permission to reproduce illustrations as 
