PREFACE XV 



Arts and Sciences. He has carefully read all of the manu- 

 script and the page proofs of the " Plant Biology." 



We are indebted to Dr. H. J. Webber, Professor E. O. 

 Fippin, and others at Cornell University, for valuable ma- 

 terial and illustrations for the chapter on Plant Propagation. 

 We wish, also, to express our hearty appreciation of the 

 generous permission of Henry Holt & Co. to use some of the 

 material published in Peabody's " Laboratory Exercises in 

 Anatomy and Physiology." We are fortunate, too, in secur- 

 ing from the New York Botanical Garden photographs for 

 the frontispiece, and for several fine cuts in the text, and from 

 Professor E. M. East of Harvard University the cut for Fig. 

 52, " Plant Biology. " Miss Mabelle Baker, Miss Clara Lang, 

 Miss Margaret Cutler, and Miss Grace Gamble, students in 

 our first-year classes, have kindly prepared for us the figures 

 on which their several names appear. 



We have been especially fortunate also in securing the 

 assistance of experts who have read much of the manuscript 

 of the " Animal and Human Biology " and many of the proof 

 sheets. Dr. E. P. Felt, New York State Entomologist, Mr. 

 E. R. Root, author of "A. B. C. of Bee Culture," and 

 Professor Glenn W. Herrick of Cornell University, have given 

 us valuable criticism of the chapter on Insects. Dr. W. T. 

 Hornaday, Director of the New York Zoological Park, has 

 read the chapters on Birds and Fishes. To Mr. J. M. John- 

 son, Head of Department of Biology of the Bushwick High 

 School, we are also indebted for suggestions relating to Birds. 



Much of the manuscript of the chapter on Foods received 

 the careful criticism of the late Professor W. O. Atwater. 

 Dr. William H. Park, Director of the Laboratories of the 

 New York City Board of Health, and Dr. Thomas Spees 

 Carrington, Secretary of the National Association for the 

 Study and Prevention of Tuberculosis, have given invaluable 



