Elementary Biology, Plant, Animal, Human

cient sleep should be continually emphasized. If boys and girls can be led to conform their daily habits to the principles of healthy living, the course in biology will have its highest justification.

In the treatment of Stimulants and Narcotics, the authors have tried to state in simple language the conclusions of experts regarding the effect of tobacco and alcohol, and to present the strongest scientific arguments against the use of these substances which are so injurious to growing youths.

No study of human biology should be allowed to leave in the mind of the student the idea that he is merely a chemical engine adapted only for the generation of a certain amount of physical energy. The primary object of all secondary education should be the development of character and efficiency, and the true teacher ought to find opportunity again and again to touch the individual life of the young student. Especially should this be true in the study of biology. Growing boys and girls ought to come to feel, as they have never felt, that they have in their keeping a most complex and wonderful piece of living machinery which can be easily put out of order or even wrecked. But, on the other hand, they should see that if the bodily machine is well cared for, it is capable of splendid work which may help to increase the sum total of human efficiency and happiness.

In the preparation of this book the authors have received a great many suggestions from the teachers in their own departments and those of other schools. Our thanks are due to Miss M. Helen Smith of the Manual Training High School, Brooklyn, N.Y., for several laboratory outlines which formed the basis of corresponding studies in the following pages. The authors have been especially fortunate in securing the constructive criticism of Dr. C. Stuart Gager, Director of the Brooklyn Botanic Garden of the Brooklyn Institute of

Arts and Sciences. He has carefully read all of the manuscript 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 material 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 securing 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. Johnson, 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

assistance in the preparation of the chapter on microörganisms. A considerable part of the "Human Biology" was critically 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.

The American

To Mr. E. R. Sanborn of the New York Zoölogical Park, and to Mr. A. E. Rueff of the Brooklyn Museum, we are indebted for their skillful photography. 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 make use of illustrative material. Cost prices for the items on the list of laboratory apparatus and equipment were kindly furnished us by Bausch & Lomb, Kny-Scheerer, and O. T. Louis; from these prices the estimates on pp. 173 to 177, Appendix I, were prepared.

J. E. P.

December 31, 1912.

A. E. H.