Vegetative Mutations. 617 



character is only displayed after fertilization; but that 

 the process should be its result, by no means folkjws from 

 this. The moment of appearance evidently tells us notli- 

 ino- about the preparation which may have prcccdccl it. 

 This may have occurred during the sexual life, or may 

 even have extended back into the vegetative stage. 



The phenomena of sectorial variation, which are l)est 

 known amongst striped flowers and variegated lea\es 

 (see page 114), but which have also been observed else- 

 where, and especially in the sectorial segregation of hy- 

 brids support the latter view. I refer to the instance de- 

 scribed above (page 276), of a variegated bud-variation 

 in an oak. A variegated twig occurred on a Inish whose 

 leaves were otherwise quite green. But the point of 

 insertion of the twig occurred on a variegated longitu- 

 dinal stripe on the branch which produced it. The change 

 therefore had not taken place in the actual origin of the 

 bud, but long before. The term bud-variation is there- 

 fore, in such cases, not strictly applicable. 



We can apply this instance to the appearance of mu- 

 tations in general and say that the moment of the actual 

 appearance of the character is preceded by a shorter or 

 a longer period in which the change, although complete, 

 was still in a latent condition. If, for instance, we are 

 dealing with a transformation in flowers, a sectorial and 

 a bud-mutation could occur without becoming externally 

 visible. In the first part of this volume (page \23>) I 

 drew attention to the stamens with red stripes in strijK^d 

 flowers and dealt with the question whether the pollen 

 grains themselves might not difl"er with regard to this 

 mark, some of them possessing this character and others 

 not. Obviously this question may be applied just as well 

 to those characters which can not be seen in the stamens. 



