THE OLDEST KNOWN MUTATION 97 



and are to be considered as sudden and definite steps " (1905, 

 pp. 190-1). 



" De Vries recalls Galton's apt comparison between variability 

 and a polyhedron which can roll from one face to another. 

 When it comes to rest on any particular face, it is in stable 

 equilibrium. Small vibrations or disturbances may make it 

 oscillate, but it returns always to the same face. These oscilla- 

 tions are like the fluctuating variations. A greater disturbance 

 may cause the polyhedron to roll over on to a new face, where 

 it comes to rest again, only showing the ever-present fluctuations 

 around its new centre. The new position corresponds to a 

 mutation" (T. H. Morgan, 1903, p. 289). 



According to De Vries, mutations have furnished the material 

 for the process of evolution. 



The Oldest Known Mutation. — A few years before the close 

 of the sixteenth century (1590), Sprenger, an apothecary of 

 Heidelberg, found in his garden a peculiar form of Chelidonium 

 majus or greater celandine. It was marked by having its leaves 

 cut into narrow lobes with almost linear tips, and by having the 

 petals also cut up. This sharply defined new form suddenly 

 appeared among the plants of Chelidonuim majus which the 

 apothecary had cultivated for many years. It was recognised 

 by botanists as something quite new, and eventually it got the 

 name Chelidonium laciniatum ; it was not to be found wild, 

 or anywhere except in the Heidelberg garden. But from the 

 first this new cut-leaved celandine proved constant from seed. 

 It has been naturaHsed in England and other countries, and is 

 sometimes now found as an "escape." Its origin by mutation 

 seems as certain as its constancy. It is further of interest to 

 note that in crosses with C. majus it follows the law of Mendel. 



Summary. — De Vries has done great service in analysing 

 the complex concept of variation ; in sharply contrasting 

 individual fluctuations and mutations ; in defining "elementary 

 species," " retrograde varieties," and "ever-sporting varieties"; 



7 



