vi PREFACE 



C. H. Nowlin, Central High School, Dr. John W. Scott, 

 Westport High School, 'and Professor A. E. Shirling, 

 Manual Training High School, all of whom read both 

 manuscript and proofs, have been incorporated. Consid- 

 erable material for the Practical Work, including the res- 

 piration experiment (page 101) and the reaction time 

 experiment (page 323), were contributed by Dr. Scott. 

 Professor Nowlin's suggestions on subject-matter and 

 methods of presentation deserve special mention. To 

 these and many others the author makes grateful 

 acknowledgment. 



F. M. W. 



MISSOURI STATE NORMAL SCHOOL, 

 SECOND DISTRICT, May i, 1909. 



