76 Plant-Breeding 



forms are produced from quick sudden leaps. The new 

 type is formed regardless of fluctuating variability, but 

 the new form becomes a center of fluctuating variability 

 similar to that around the parental form. 



7. The mutations take place in nearly all directions. 



De Vries says, "Some of my new types are stouter and 

 others weaker than their parents, as shown by gigas and 

 albida. Some have broader leaves and some narrower 

 (lata and oblonga). Some have larger flowers (gigas) or 

 deeper yellow ones (rubrinervis) or smaller blossoms 

 (scintillans) or of a paler hue (albida). In some the 

 capsules are longer (rubrinervis) or thicker (gigas) or 

 more rounded (lata) or small (oblonga) or nearly destitute 

 of seeds (brevistylis) . The unevenness of the surface of 

 the leaves may increase as in lata or decrease as in Icevi- 

 folia. The tendency to become annual prevails in ru- 

 brinervis, but gigas tends to become biennial. Some are 

 rich in pollen, while scintillans is poor. Some have large 

 seeds, others small. Lata has become pistillate, while 

 brevistylis has nearly lost the faculty to produce seeds. 

 Some undescribed forms were quite sterile, and some I 

 observed which produced no flowers at all." 



Examples of mutations. Shirley poppy. Lock cites 1 

 the Shirley poppy as a mutation from the wild field poppy 

 (Papaver Rhoeas) so common in England. It was first 

 noticed in 1880 by the Rev. W. Wilks, Vicar of Shirley, 

 near Croydon, England, in a patch of the wild forms 

 growing in a waste corner of his garden. There suddenly 

 appeared a solitary flower showing a very narrow border 



1 " Recent Progress in the Study of Variation, Heredity, and Evolu- 

 tion," p. 133. 



