618 Validity of the Doctrine of Mutation. 
I shall not pursue this train of thought further; but 
this much seems to be clear, that germinal variations may 
be the results of changes which have already taken place 
Fig. 137. Green Dahlia. A branch whose terminal inflores- 
cence b as well as the lateral one b' have become green, 
as in the remaining parts of the plant, whilst a branch 
has arisen at a from an axillary bud, bearing double red 
inflorescences of normal structure and without a trace of 
virescence. a', flowering and a", a bud. See above, p. 
92, Fig. 14 (1902). See also pp. 628-629. 
in the pollen- and egg-cells ; and that these changes them- 
selves may have had their origin before the development 
