XVI PREFACE 



assistance in the preparation of the chapter on microorgan- 

 isms. A considerable part of the " Human Biology " was crit- 

 ically read by Dr. F. C. Waite of the Western Reserve Medical 

 School, by Mr. Harold E. Foster of the English Department 

 of the Morris High School, and by the late Miss Martha F. 

 Goddard of the Morris High School, to whose memory these 

 volumes are dedicated. 



To Mr. E. R. Sanborn of the New York Zoological Park, 

 and to Mr. A. E. Rueff of the Brooklyn Museum, we are 

 indebted for their skillful photography. The American 

 Museum of Natural History, the Brooklyn Museum, the 

 National Aubudon Society, Doubleday, Page & Co., Dodd, 

 Mead & Co., Kny-Scheerer Co., Dr. C. F. Hodge of Clark 

 University, Dr. H. A. Kelly of Johns Hopkins Medical 

 School, Mr. C. W. Beebe of New York Zoological Park, and 

 others, have permitted us to majce use of illustrative material. 



Cost prices for the items on the list of laboratory appa- 

 ratus and equipment were kindly furnished us by Bausch & 

 Lomb, Kny-Scheerer, and 0. T. Louis ; from these prices the 

 estimates on pp. 173 to 177, Appendix I, were prepared. 



J. E. P. 

 A. E. H, 



December 31, 1912. 



