34 



SCIENCE. 



[N. S. Vol. XXII. No. 550. 



terial, and have the methods of their solu- 

 tion only changed ? Or have the problems 

 themselves become different ? 



To reply to this question is not easy, 

 and the answer must vary with the point 

 of view of the one who makes it. For 

 morphology is yet far from being an exact 

 science, the results of which force them- 

 selves upon us with the compulsion of 

 necessity.^ This is due to the difficulty of 

 the materials, a difficulty which compels 

 us to seek for hypotheses and other sub- 

 jective means of explanation. It thus 

 comes 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 con- 

 cerning the fundamental problems of mor- 

 phology are certainly far from being ap- 

 proved by all morphologists. 



We may, indeed, say that, apart from 

 minor differences, there are in morphology 

 two main trends of thought which, appar- 

 ently 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 

 relations; 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 morphology appears to 

 be, in the nature of the case, a formal one, 

 and as a matter of fact has been in its his- 

 torical development. But in spite of this 

 fact this definition is historically justified, 

 for it designates the tendency of morphol- 

 ogy which regards form as something 

 which stands alone for itself, and takes 

 cognizance neither of the functions of or- 

 gans nor of how they have arisen. This 

 formal morphology arose at first out of the 

 necessities of taxonomy. There had first 



to be' contrived a terminology for the dis- 

 tinction and description of single plant 

 forms. From this function morphology 

 soon, however, became distinct, thus con- 

 stituting an independent discipline which 

 on its part had served 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 deter- 

 mining what was common to the most vari- 

 ous forms and was accordingly directed 

 toward more general questions; morphol- 

 ogy taught, as Goethe expressed^ it, 'Die 

 Glieder der Pflanzen im Zusammenhange 

 zu betrachten^ und so das Ganze in der An- 

 schauung gewissermassen zu beherrschen. ' 

 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, mor- 

 phological research showed that the paral- 

 lelism between different plant forms could 

 be understood most easily under the as- 

 sumption 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 of descent has also reacted upon 

 morphological research, to such an extent^ 

 indeed, that it has been held that phylo- 

 genetic research is to be regarded as the 

 sole business of morphology. Thus, for 

 example, Scott has said : 



The object of 'modern morphological botany is 

 the accurate comparison of plants, both living and 

 extinct, with the object of tracing their real rela- 

 tionships with one another, and thus of ultimately 

 constructing a genealogical tree of the vegetable 

 kingdom. The problem is thus a purely historical 



