158 STERILE AND FERTILE REGIONS 
petals, etc., originate on the stem, they were all included under the one 
general idea of “leaf.” In the words of Sachs, Goethe’s doctrine could 
only make its way to logical consistency and clearness of thought by 
deciding for the one or the other meaning of the word: he must either 
assume that the different leaf-forms, which were regarded as alike only 
in the idea, were really produced by change of a previous form—a 
conception that at once presupposes a change of the species in time :— 
or he must entirely adopt the position of the idealistic philosophy, in 
which the idea and the reality coincide. In this case the assumption 
of a change in time was not necessary: the metamorphosis would remain 
an ideal one, a mere mode of view; the word leaf would then signify 
only an ideal fundamental form, from which the different forms of leaves 
actually observed may be derived, as De Candolle’s constant species, from 
an ideal type. 
Though Goethe did not himself decide finally for either ‘of these 
alternatives, the introduction of a theory of Descent, and a general belief 
in transmutation of species, went far towards clearing away any such 
ambiguity. In its light the facts seemed to point definitely towards a 
conception of a real transformation, and this point of view came into 
prominence pari passu with a better knowledge of the lower Vascular 
Plants, where leaf-differentiation is less fully carried out and gradual transi- 
tions are to be seen between vegetative leaves and sporophylls. Accordingly, 
it seemed to be the plain and simple reading of the facts to accept the 
metamorphosis as a change which had actually been effected in the course 
of descent. The natural progression shown in the life of the individual 
seemed to be that already described as progressive by Goethe: it was 
natural to accept this in terms of the theory of descent as progressive 
in the race also. On this basis the floral appendages would be held to 
be essentially foliage leaves, but altered in character to subserve propa- 
gation; and the pollen-sacs and ovules which they bear accessories which 
are added to the already existent foliar parts. The experience of zoologists 
had its influence in apparently confirming this position. The analogies 
between the two organic kingdoms are at many points so close that the 
general conclusions of the animal embryologists seemed readily applicable 
to plants also. If the ontogeny of the higher animals is found often to 
recapitulate the history of the race, should not the same conclusion apply 
also to the higher plants? Moreover, such a view presented itself as a 
mere continuation of the theoretical opinion of Goethe: the progressive 
metamorphosis which he recognised would figure, accordingly, as a principal 
feature in the evolution not only of the individual but of the race. Thus 
regarded the sporophyll of the individual plant would be an altered 
foliage leaf, and its origin by descent would be the same: the difference 
of their development would then Jie in the presence of the sporangia, 
which brings correlative restriction of the foliar development in its train. 
This position may seem satisfactory so long as the Higher Vascular 
