THE STUDY OF PLANTS IN ANCIENT AND MODERN TIMES. 17 



thousands of different sorts of forms, and of tracing the history of plants and 

 vegetable life all over the earth. 



The various lines of botanical research described in the foregoing pages, with 

 their particular problems and objects, have but slight connection one with another. 

 They run side by side along separate paths, and it is only occasionally that a 

 junction is apparent which establishes a communication between one path and 

 another. The subject-matter, however, is always the same. Whether we have 

 to do with the perfected form or with its growth, whether we try to interpret the 

 processes of life or to trace the genealogy of the vegetable kingdom, we always 

 start from the forms of plants; and the ultimate result is never anything more than 

 a description of the varying impressions which we receive at different times from 

 the objects observed, and which we endeavour to bring into mutual connection. 

 All the different departments of botany are accordingly more or less limited to 

 description; and even when we endeavour to resolve vital phenomena into 

 mechanical processes we can only describe, and not really explain, what happens. 

 The processes which we call life are movements. But the causes of those move- 

 ments, so-called forces, are purely subjective ideas, and do not involve the concep- 

 tion of any actual fact, so that our passion for causality is only ostensibly gratified 

 by the help of mechanics. Du Bois Reymond is not far wrong when he follows 

 out this train of thought to the conclusion (however paradoxical it may sound) 

 that there is no essential difference between describing the trajectory (or particular 

 kind of curve) in which a projectile moves on the one hand, and describing a beetle 

 or the leaf of a tree on the other. 



But even though the ultimate sources of vital phenomena remain unrevealed, 

 the desire to represent all processes as effects, and to demonstrate the causes of 

 such effects — a desire which is at the very root of modern research — finds at least 

 partial gratification in tracing a phenomenon back to its proximate cause. In the 

 mere act of linking ascertained facts together, and in the creation of ideas involv- 

 ing interdependence among the phenomena observed, there lies an irresistible charm 

 which is a continual stimulus to fresh investigations. Even though we be sure 

 that we shall never be able to fathom the truth completely, we shall still go on 

 seeking to approach it. The more imaginative an investigator the more keenly 

 is he goaded to discovery by this craving for an explanation of things and for 

 a solution of the mute riddle which is presented to us by the forms of plants. 

 It is impossible to overrate the value and eflficiency of the transcendent gift of 

 imagination when applied to questions of Natural History. Thus when we inquire 

 whether certain characters noted in a plant are hereditary, constant, and inalienable, 

 or are only occasioned by local influences of climate or soil, and hence deduce 

 whether the plant in question is to be looked upon as a species or a variety; when 

 we conclude from the fact of a resemblance between the histories of the develop- 

 ment of various species that they are related, and place them together in groups 

 and series; when we unravel the genealogies of different plants by comparing 

 forms still living with others that are extinct; when we try to represent clearly 



