82 PLANT MORPHOLOGY 



about that views not only concerning the goal of morphology, but 

 also as to the way in which this goal is to be reached, are widely 

 diverse, and my own views concerning the fundamental problems of 

 morphology are certainly far from being approved by all morpholo- 

 gists. 



We may, indeed, say that, apart from minor differences, there are 

 in morphology two main trends of thought which, apparently, at 

 least, are opposed to each other, one of which we may denominate 

 formal, and the other causal. Causal morphology is that the aim of 

 which is to determine the causes, in the widest sense, of form-rela- 

 tions; this kind of morphology is the youngest, and is far less widely 

 diffused than the formal. To us of a later period it may seem like a 

 remarkable pleonasm to speak of a "formal morphology." Mor- 

 phology is, of course, the doctrine of form, and therefore any mor- 

 phology appears to be, in the nature of the case, a formal one, and, 

 as a matter of fact, has been, in its historical development. But in 

 spite of this fact, this definition is historically justified, for it desig- 

 nates the tendency of morphology which regards form as something 

 which stands alone for itself, and takes cognizance neither of the 

 functions of organs nor of how they have arisen. This formal morpho- 

 logy arose at first out of the necessities of taxonomy. 1 There had first 

 to be contrived a terminology for the distinction and description of 

 single plant forms. From this function morphology soon, however, 

 became distinct, thus constituting an independent discipline which, 

 on its part, had done taxonomy a more important service than one 

 might have at first expected. For while taxonomy, in order to find 

 its way amid the maze of plant forms, had to keep in view the differ- 

 ential characters and the separation of single forms from each other, 

 morphology found itself under the necessity of determining what was 

 common to the most various forms, and was accordingly directed 

 toward more general questions; morphology taught, as Goethe ex- 

 pressed it, " Die Glieder der Pflanzen im Zusammenhange zu betrach- 

 ten, und so das Ganze in der Anschauung gewdssermassen zu be- 

 herrschen." It resulted in the knowledge that, when we regard plants 

 singly, manifold as their parts appear, they may yet be referred to 

 a few elementary forms, and further, morphological research showed 

 that the parallelism between different plant forms could be under- 

 stood most easily under the assumption which we designate the 

 theory of descent. The establishment of the theory of descent was 

 the result of the morphological research. This we must here especially 

 emphasize, for it shows what significance morphology has gained 

 in respect to our general conception of organisms. But the theory 



1 How far the trends of morphology and taxonomy have of recent years drawn 

 apart is shown, e. g., in Engler's Syllabus of the Families of Plants, the most recent 

 review of the plant kingdom as a whole. For the most part, the results of develop- 

 mental researcli remain entirely disregarded in this work. 



