vi BIOLOGY AND HUMAN LIFE 



by a few questions that are designed to represent the pupil's 

 point of view. The questions at the ends of the chapters, to- 

 gether with the outlines and summaries, represent rather the 

 teacher's point of view ; they do not call for a mere reproduction 

 of the matter in the text, but are intended to stimulate the pupil 

 to resurvey the subject matter, to reorganize it, and to reorient 

 it for himself. The organization of the text, the questions, and 

 the outlines carry for the teacher implicit suggestions as to what 

 procedure will best furnish the concrete observation, experimen- 

 tation, demonstration, etc. needed for an understanding of the 

 ideas treated ; and for the pupils they carry something more than 

 explicit suggestions as to the meaning of reliable method in the 

 solving of various problems. The reference readings are mostly 

 from materials readily obtained from government agencies. 



The text has been carefully checked against Thorndike's word 

 list for ninth-grade pupils. New words that do not have their 

 meanings revealed by the context are defined, and the Index will 

 serve as a pronouncing vocabulary as well as a reference to defi- 

 nitions or explanations. Many of the illustrations are taken 

 from the author's "Elementary Biology," some of them with 

 slight modifications; many, however, have been made espe- 

 cially for this book, and some are for the first time made acces- 

 sible to high-school teachers and pupils, such as the Ancon type 

 of sheep mutation and the arterial system of the arm as shown 

 by the X rays. Acknowledgment for photographs and other 

 materials is made in connection with the several illustrations, 

 but the author wishes here to express his deep appreciation of 

 the splendid cooperation received from the various scientists 

 and institutions, as well as for the patient efforts of the artists 

 who have assisted in developing many of the special drawings— 

 Mr. F. Schuyler Mathews, Mr. Frank M. Wheat, Miss Marcelle 

 Roigneau, and Mr. Carl A. Schwarze. 



B.C.G. 



o 



