PREFACE. 



Botanical Science is made up of three distinct 

 branches of knowledge, Classification founded on Mor- 

 phology, Phytotomy, and Vegetable Physiology. All 

 these strive towards a common end, a perfect under- 

 standing of the vegetable kingdom, but they differ en- 

 tirely from one another in their methods of research, and 

 therefore presuppose essentially different intellectual en- 

 dowments. That this is the case is abundantly shown by 

 the history of the science, from which we learn that up to 

 quite recent times morphology and classification have 

 developed in almost entire independence of the other two 

 branches. Phytotomy has indeed always maintained a 

 certain connection with physiology, but where principles 

 peculiar to each of them, fundamental questions, had to 

 be dealt with, there they also went their way in almost 

 entire independence of one another. It is only in the 

 present day that a deeper conception of the problems 

 of vegetable life has led to a closer union between 

 the three. I have sought to do justice to this historical 

 fact by treating the parts of my subject separately ; but in 

 this case, if the present work was to be kept within suit- 

 able limits, it became necessary to devote a strictly limited 

 space only to each of the three historical delineations. It 

 is obvious that the weightiest and most important matter 

 only could find a place in so narrow a frame, but this I do 



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