VI PREFACE 



light of our modern scientific knowledge. While these are 

 not the matters the sijeeialist needs most to know, I cannot 

 but think that he also will find advantage in entering upon 

 his work through this broader portal. 



The book is supposed to be used in conjunction with organ- 

 ized laboratory work, and to be read for the sake of connecting 

 the discontinuous though invaluable knowledge won by expe- 

 rience in the laboratory with the systematized content of the 

 science, the two being welded thus into one intellectual unit. 

 This assumption of contemporaneous laboratory work, sup- 

 posed always to precede the reading, will explain a much 

 greater generality or abstractness of treatment than would 

 otherwise be suitable. Since, however, teachers differ much 

 in their ideas as to desirable sequence and emphasis, I have 

 treated the various topics in the form of semi-independent 

 essa3's, intended to be separately understandable. The method 

 involves repetition, but permits omission, by sections, where 

 the material is found overabundant, as it will be for most 

 students, though it should not prove so for the best. 



The fact that the book is prepared for the general student, 

 whose psychology I have long been studying (when I might 

 have been better employed, as I know my investigating col- 

 leagues think), will explain some features not otherwise obvi- 

 ous. Thus, structure is treated before function, because that 

 is the more practicable waj', even though the reverse is more 

 logical. Again when the seemingly obvious is elaborated, it 

 is because experience has shown how different is the aspect 

 of those matters to tlie youthful beginner and the mature 

 specialist. Further, if not all of the newest matters are in- 

 cluded, it is not necessarily because I do not realize their 

 scientific importance, but because, in most cases, they seem 

 either not sufficiently established or not sufliciently prominent 

 for inclusion in an introductory course. The test of the value 

 of the book will be found not in whether my colleagues con- 

 sider it a well-proportioned compendium of botanical fact, but 

 in whether it leads students to pursue the subject in an inter- 

 ested and spontaneous spirit. 



