vi ACKNOWLEDGMENT 



The large number of line drawings is intended to simplify 

 matters of structure for the beginner who would have difficulty 

 in selecting the essential points of a more detailed drawing or 

 photograph. Since the object of illustrations in an elementary 

 text is to call attention to essential facts, the simple diagrammatic 

 outlines and complete labeling found in this book are worthy of 

 notice. It is hoped also that a reasonable use of line drawings 

 will help the pupil in his own work by affording models which 

 he can easily approximate. 



The economic applications of biology have been given very full 

 treatment, especially as to their bearing on agriculture and civic 

 problems. 



The scope of the matter presented is broad enough so that the 

 teacher can select what seems most important, and still be sure 

 of covering any requirement in any elementary biology syllabus. 

 On the other hand the attempt has been made not to burden the 

 pupil with matter required for advanced biology only. 



ACKNOWLEDGMENT 



IN offering this text book to the public, recognition is due to 

 many sources of aid and information. 



The lists of references appended to the various chapters fulfill 

 the double purpose of indicating some of the authorities which 

 have been consulted and of telling the student where fuller in- 

 formation may be obtained. 



The cuts, in so far as they are not original, are credited to the 

 proper sources in each case. In many cases, these are changed 

 in some degree, to conform to the uses of the text. 



The author is especially indebted to the cheerful assistance of 

 his wife in the laborious task of reading and correcting the manu- 

 script and proof, and to his fellow teacher, Miss C. E. Reed,* for 

 many helpful suggestions as to content and arrangement. 



If there be aught of use or value in this book let it be to the 

 credit of the authorities consulted and the help received; for its 

 many shortcomings the author alone is responsible. 



T. J. MOON 



