PREFACE TO THE SECOND EDITION 



In this edition the treatment of the subject is essentially the 

 same as in the first, but the advance of botanical science has 

 necessitated constant alterations throughout the text and many 

 of the topics have been completely recast. The writer believes 

 that there is no better way of cultivating the power of observa- 

 tion and developing the reasoning faculties than through a study 

 of the common forms of plant life. So the purpose of the book 

 is not to present a series of studies that may be followed in the 

 laboratory, but rather to put the student in a position to under- 

 take new studies with the least assistance. Acknowledgments 

 are due to Professors Ira D. Cardiff, Jean Broadhurst and Dr. 

 Bernard O. Dodge for their valuable suggestions and assistance, 



Carlton C. Curtis. 



Columbia University, 

 August, 1910. 



vn 



