110 Atarisni. 
picions indicated above. I mean that they occur so rarely 
and in so few individuals that the possibility of a previous 
cross, by means of insects, with the pollen of allied forms, 
even if growing a long way off, can never be quite ex- 
cluded. It is only in cases in which, as in that of Ociw- 
tlicra sciutiUaiis (Vol. I, pp. 245 and 377), a species pro- 
duces a large number of atavistic individuals every year, 
that the phenomenon easily lends itself to experimental 
study. 
On account of the circumstances indicated, it is not 
possible to say whether atavism in plants propagated by 
seed is a common or a rare phenomenon. It is certainly 
much rarer than the practical gardener usually imagines. 
I have observed in my cultures a number of cases which 
might have been called atavistic with more or less cer- 
tainty, but only the cases of regularly inconstant races, 
such as those of Plantago and Linaria, and the phenom- 
ena presented by striped flowers, to be described shortly, 
seem to me to be sufficiently well established to be ad- 
duced as instances of atavism. 
Atavism by bud-variation, on the other hand, is a 
well-known phenomenon. One of the best instances is 
shown in Fig. 16. It represents a vertical branch of a 
bush of Ccphalota.rus pedunculata fastigiata (Podocarpus 
Koraiana Hort}. Below the middle of the figure can 
be seen the place where a branch has been cut off, and 
from the side of its base some lateral branches have arisen 
with flat spreading leaves (Fig. 16 A). 1 The variety 
Fastigiata has erect branches only and their leaves are 
inserted on all sides ; but the branches at A have the 
structure of the parent species, C. pedunculata ; their 
1 For a series of interesting experiments relating to this subject 
see Mutations ct traumatismcs by L. BLARINGHEM (Note of 1909). 
