ON GOETHE'S SCIENTIFIC RESEARCHES. 41 



researches. If we only examine what has really been accom- 

 plished by the help of the ideas which he contributed to science, 

 we shall be struck by the very singular relation which they bear 

 to it. No one will refuse to be convinced if you lay before him 

 the series of transformations by which a leaf passes into a 

 stamen, an arm into a fin or a wing, a vertebra into the occipital 

 bone. The idea that all the parts of a flower are modified leaves 

 reveals a connecting law which surprises us into acquiescence. 

 But now try and define the leaf-like organ, determine its essential 

 characteristics, so as to include all the forms that we have named. 

 You will find yourself in a difficult}', for all distinctive marks 

 vanish, and you have nothing left, except that a leaf in the 

 wider sense of the term is a lateral appendage of the axis of 

 a plant. Try then to express the proposition 'the parts of the 

 flower are modified leaves ' in the language of scientific defi- 

 nition, and it reads, ' the parts of the flower are lateral appen- 

 dages of the axis.' To see this does not require a Goethe. So 

 again it has been objected, and not unjustly, to the vertebral 

 theory, that it must extend the notion of a vertebra so much 

 that nothing is left but the bai^e fact a vertebra is a bone. We 

 are equally perplexed if we try to express in clear scientific- 

 language what we mean by saying that such and such a part of 

 one animal corresponds to such and such a part of another. We 

 do not mean that their physiological use is the same, for the 

 same piece which in bird serves as the lower jaw, becomes 

 in mammals a tiny tympanal bone. Nor would the shape, the 

 position, or the connection of the part in question with other 

 parts serve to identify it in all cases. But yet it has been found 

 possible in most cases, by following the intermediate steps, to 

 determine with tolerable certainty which parts correspond to 

 each other. Goethe himself said this very clearly : he says, in 

 speaking of the vertebi-al thory of the skull, ' Such an aper^u, 

 such an intuition, conception, representation, notion, idea, or 

 whatever you choose to call it, always retains something 

 esoteric and indefinable, struggle as you will against it ; as a 

 general principle, it may be enunciated, but cannot be proved y 

 in detail it may l>e exhibited, but can never be put in a cut and 



