ON Goethe's scientific reseakches. 47 



as particularly convincing I The poetic turn of mind is 

 very marked even in his morphological researches. If 

 we only examine what has really been accomplished 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 con- 

 necting 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 difii- 

 culty, 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 

 appendages of the axis.' To see this does not require a 

 Groethe. 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 bare 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 a 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 toler- 



