INTRODUCTION 13 



in all its numberless ramifications. Such a complete 

 classification can never be hoped for, inasmuch as the 

 plants which now exist are in many cases but scattered 

 remnants of groups once much more numerous than 

 at present, which have left no recognizable fossil traces. 

 Some forms are so much isolated, and have so little in 

 common with other groups, that at present any attempt 

 to give them their proper place in the system is little 

 better than pure guesswork. 



It is thus clear that at present the question is very 

 far from settled ; indeed, hardly more than a beginning 

 has been made in the establishment of a system which 

 can be said to represent real genetic relationships. Our 

 present knowledge of the vast majority, even of many 

 of the commoner plants, is extremely imperfect, being 

 confined often to purely superficial characters. It is 

 necessary to investigate thoroughly the structure and 

 development of a great many forms before the data 

 can be had for constructing a classification which we 

 can hope will be permanent, and a beginning only of 

 this vast work has yet been made. In addition to the 

 careful structural study of the existing plants, a thor- 

 ough examination of the fossil species is necessary, 

 involving even more arduous labor than does the in- 

 vestigation of living forms. Palseo-botany has already 

 yielded results of the greatest importance, and it is but 

 reasonable to hope that further investigations will add 

 much to the materials already accumulated. These 

 researches must, however, consist of something more 

 than mere collecting and naming of dubious fragments. 

 What is imperative is a more complete knowledge 

 of the remains already discovered, rather than the 



