Vegetative Mutations. 617 
character is only displayed after fertilization; but that 
the process should be its result, by no means follows from 
this. The moment of appearance evidently tells us noth- 
ing about the preparation which may have preceded it. 
This may have occurred during the sexual life, or may 
even have extended back into the vegetative stage. 
The phenomena of sector ial variation, which are best 
known amongst striped flowers and variegated leaves 
(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 bush 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 123) I 
drew attention to the stamens with red stripes in striped 
flowers and dealt with the question whether the pollen 
grains themselves might not differ 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. 
