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 Yace. 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 lie 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 



