PREFACE. V 



It is suggested that the teacher, at the beginning of the work, 

 take some account of the time to be allotted to the different 

 subjects of the course. For example, in a 20-weeks' course, 

 7 to 8 weeks could be devoted to physiology, 5 or 6 weeks 

 could be devoted to general morphology ; while 6 or 8 weeks 

 could be devoted to the study of plant families. As the work 

 progresses it can be easily seen whether or not all the exercises 

 and demonstrations can be gotten in during the allotted time. 

 If the time is too short in some cases, the teacher can then 

 arrange to omit certain of the exercises in each chapter, so that 

 as a whole the work can be completed in the desired time. 

 Some of the chapters are intended for reading and reference 

 only. These are indicated at the beginning of the chapters in 

 question. They should not be taken into account when consid- 

 ering the amount of practical work to be done by the pupil. 



Cornell University, 

 January, 1900. 



