PREFACE V 



work. Directions for laboratory study, if included at al! in a 

 textbook, are necessarily so placed as unfortunately to suggest the 

 relative unimportance of the laboratory. Secondary school work 

 in a natural science should invariably have laboratory study as its 

 central feature, and the textbook should be considered an accessory 

 which helps to elaborate and to tie together the knowledge obtained 

 from the study of the objects themselves. Ample time should be 

 allowed for laboratory work, and whenever possible double periods 

 should be arranged for this purpose. In general, too, the labora- 

 tory study of a topic should precede the textbook study and recita- 

 tion upon that particular topic ; but this rule cannot always be 

 rigidly insisted upon, and here as elsewhere the judgment of the 

 teacher must play an important role. The laboratory directions 

 given in the present book (Appendix I) are intended to be only 

 suggestive. It may well be that in places the teacher will find it 

 advisable to abbreviate. In many more places it will be necessary 

 to supplement by additional directions and by the demonstration 

 of structures which cannot well be studied, or of experiments which 

 cannot well be carried on, by the pupils individually. Much the 

 greater part of the work outlined can be done with very simple 

 apparatus, including hand lenses or dissecting microscopes, of 

 which there should be one for each student. Some of the study 

 necessarily involves the use of a compound microscope. We do 

 not feel, however, that the secondary school student should spend 

 any considerable part of his time with the compound microscope, 

 and in general we recommend that this instrument be used only 

 for demonstrations arranged by the teacher. If the school is suf- 

 ficiently equipped, there are certain points, for example in the 

 study of bacteria, at which individual study with the aid of the 

 compound microscope is helpful. Even in the study of bacteria, 

 however, this individual work may be omitted and yet with the aid 

 of a few demonstrations the student may obtain a very satisfactory 

 conception of the nature and activities of the organisms in question. 

 A word may be added regarding work out-of-doors. There is 

 no way in which an enthusiastic teacher can more successfully 

 impart his enthusiasm to his pupils than by means of field work. 

 The successful teacher of botany is the one who induces his stu- 

 dents to explore the world of plants for themselves. Field work, 



