IV PKKPACE. 



rally great difference of opinion among practical teachers. 

 The plan here adopted is the one that seems to the writer 

 to have best stood the test of experience in the grades for 

 ■which the exercises were prepared. It is hoped that in 

 spite of mistakes and imperfections, sure to be brought to 

 light if the book is used, it may nevertheless prove service- 

 able to a rapidly increasing numbei; of teachers who are 

 desirous of improving existing methods of instruction. 

 To Dr. Erwin F. Smith of the United States Department 

 of Agriculture, Miss Effie A. Southworth of Barnard 

 College, and Mr. W. H. Rush of Harvard University, who 

 besides reading the proofs have critically reviewed and 

 tested the greater part of the practical work, and to others, 

 especially of my former students, I am under obligation 

 for assistance and encouragement which are here gratefully 

 acknowledged. 



In the second edition, prepared in response to helpful 

 suggestions from many teachers, a glossary and index, 

 together with a chapter on fungi, have been added and 

 several minor changes introduced. The arrangement re- 

 mains substantially as before, but teachers who prefer to 

 start with the simpler forms and proceed to the more 

 highly developed ones can readily do so by beginning with 

 the section on algae, instead of following the order of the 

 book. To those who approach the work in a scientific 

 spirit, it is superfluous to say that the student's intellectual 

 life has a developmental history which it is quite as need- 

 ful to take into account as the genetic succession of plants. 

 There can hardly be more interesting problems than those 

 presented to the teacher in his relation to this higher realm 

 of biological science. 



