17 
as to the principle of natural classification for which I could find no support 
in Darwin, Harcket, Eveier, Hawwier or others. In the following pages, it 
is my desire to explain GorTuE’s “ Metamorphose der Pflanzen,” and to refer 
to the principle of natural classification found, as I believe, in his work. To 
understand his “ Metamorphosenlehre ” we must have a just and adequate idea 
of his Blatt which is as it were the hero of his work. The interpretation 
of this Blatt is the principal subject of this: paper. 
The ‘“ Metamorphose der Pflanzen,” that celebrated work of the great poet, 
when looked at from the point of view of modern scientific knowledge, certainly 
contains many mistakes in minute details; but the principal idea in it, viz., 
that, although there are many kinds of vegetable organs, they are after all 
modifications of one and the same organ - Blatt which becomes, according to 
different circumstances, a foliage leaf, or a sepal, or something else, i.e. “die 
GorTHEsche Lehre von der Einheit aller Pflanzengestaltung” is generally 
considered to be on the whole a quasi-indisputable theory. Now, what is 
that one and the same organ — Blatt proposed by GoETHE? To this question, 
many authors have given varying answers. GREEN* says in his History of 
Botany that “his (Ga@run’s) idea were not put before his readers very clearly, 
and left them sometimes uncertain whether he considered all leaves modifications 
of some ideal or theoretical form, or whether he held that a structure com- 
mencing its development in some particular direction might be actually diverted 
into another, and become something quite different from what it would have 
become, had its development not been interfered with.” This is an interesting 
problem, the solution of which will on the one hand lead us to see directly the 
mutual relations of vegetable organs, and on the other will make us understand 
indirectly the relationship between the species themselves. It is, therefore, not only 
a question of morphology, but also an important problem of systematic botany. 
As far as my investigation into GorTHn’s studies extends, his methods are 
generally not inductive, but often deductive, as can be seen by the following 
quotation***, 
* Green, J. R—A History of Botany (1860-1900) 1909, p. 66. 
** Conn, F.—Die Pflanzen (1896) p. 114. 
¥** Brerscuowsky, A.—Goethe, sein Leben und seine Werke, II. p. 89. 
